Finishing materials


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Finishing materials

  1. 1. Finishing Finishing materials All About Oil Based Varnish For many amateur woodworkers or hobbyists who either cannot afford spray equipment or do not have enough space in their shop to set up a spray booth to safely spray finishes like lacquers, brushing on an oil based varnish is one of the best choices for a topcoat finish. Oil based varnish does not dry very quickly, therefore it will take longer to complete a finishing project using varnish as opposed to lacquer, water based or other faster drying finishes. However, if you are an amateur or home woodworker, not a pro who has to worry about meeting a deadline, time should not be top priority, quality should. Varnish has very good resistance against abrasion, wear, heat, solvents and water vapor. Other than its slow drying time, which can also cause problems with dust getting trapped in the finish before it dries, the only other disadvantage to oil based varnish is that it tends to yellow over time. The dust problem can be taken care of by setting up a dust free finishing area in your shop and sealing it off with heavy plastic to reduce the amount of dust and sawdust in that area. The problem of yellowing cannot be handled as easily. First, most oil based varnishes are amber (yellowish) in color to begin with. This is because the oils used to make the varnish are amber. Therefore, oil based varnishes tend to somewhat change the color of the raw or stained wood when they are applied. It is not a considerable change, and unless applied over a very light colored or white stain, it is satisfactory. In fact, amber varnishes actually give darker woods like walnut and mahogany a warmer appearance. Non-amber or what are called water white finishes like some lacquers and water based finishes can leave a cold look on darker colored woods. However, if needed, there are a few water white varnishes available. One is called water white restoration varnish manufactured by H. Behlen & Bro. Nothing can really be done about yellowing of varnish over time and if you think about it, all film finishes break down in one way or another over time and have to be removed and replaced with a new finish. Tung oil yellows less over time than other oils, therefore a varnish that contains tung oil will have a tendency to yellow less over time. Oil based varnish is manufactured by cooking certain oils that can cure with resins. Once this blend of cooked oil and resin is complete, solvents are added to make it thin enough to apply and metallic dryers are added to help speed up the curing time. Initially, linseed and tung oil were used by manufactures for the curing oils and natural resins like pine and gum resins were used along with solvents like gum turpentine and mineral spirits (to thin it out) and lead used for the drier. These ingredients were not only used to make varnish, but also paint. With the exception of lead, you can sometimes still find some of these ingredients in today's oil based varnishes, but modern varnishes usually use synthetic resins which are superior in strength and longevity and curing oils that are less expensive to use in the manufacturing process along with a blend of solvents and metallic dryers like cobalt and zinc that do not cause health problems such as lead does. Wisdom Management Services (M) Sdn. Bhd. 1
  2. 2. Finishing Finishing materials Types Of Oil Based Varnishes Phenolic Resin This varnish is made with phenol (a plastic) and formaldehyde. The phenol is a solid and is made into liquid by heating it with oil and then adding in the other ingredients. When the finish is applied in a thin film and exposed to to the air, the solvent will evaporate and it will turn back to its solid form. Alkyd Resin Less expensive, this is a type of polyester resin that is combined with alcohol and acid. It is also cooked with oil to create a varnish. This is the most commonly used resin in commercial varnishes today. Polyurethane Yes, that's right. Polyurethane is classified as an oil based varnish, although some purists will disagree. Initially developed to be used as a substitute for other plastics, polyurethane has become on of the most commonly used resins in the manufacturing of many wood finishes. Polyurethane is a very tough, abrasion resistant resin. There are many types and forms of polyurethane, but the kind of polyurethane finish you are used to seeing in paint and woodfinishing supply stores is not pure polyurethane, but rather an alkyd varnish that has been modified by adding some polyurethane into it. That is why polyurethane should be classified as a varnish. Perhaps a better description would be modified varnish, but nevertheless, still varnish. It is applied and it cures in the same manner as other oil based varnishes. Contrary to what many people say about polyurethane, most modern high quality polyurethanes do not dry leaving a plastic appearance. They are available in various sheens from satin to semi- gloss to gloss and can also be rubbed to a beautiful smooth luster. Polyurethane's abrasion resistance makes it on of the most commonly used finishes today. Satin Vs.Gloss Or Semi-Gloss Throughout the years, many pieces of furniture have been finished with varnishes and other topcoat finishes. Years ago, and on much custom furniture still today, the varnish was applied and then rubbed down with steel wool or sandpaper to cut down the shine and give it a more pleasing look. Today, woodfinishing manufactures make varnishes in different levels of shine so the furniture does not have to be rubbed down after the finish has been applied thus saving many hours of hand or machine rubbing. These varnishes are sold in different sheens. Some will give the user a high gloss finish, others like a satin will have a slight gloss. All topcoat finishes start out as high gloss and if the manufacture wants to make a satin or semi-gloss finish, they take the gloss finish Wisdom Management Services (M) Sdn. Bhd. 2
  3. 3. Finishing Finishing materials and add a flattening paste into the finish along with the oils resins and other ingredients we now know are used to make varnishes. This paste is usually some kind of zinc oxide and it settles to the bottom of the can. This is why you do not have to stir a gloss varnish before it is applied, but you must stir satin or semi gloss varnishes to get the paste off the bottom of the can and mix it into the finish. The flattening paste makes the finish a little duller and prevents the light from reflecting off the surface as much as a gloss finish. The flattening paste also makes the finish less transparent, thus creating a cloudy look. If you apply too many coats of satin or semi-gloss varnish, you could actually start to obscure the grain of the wood. Whenever I elect to use a satin or semi-gloss varnish, I will use gloss varnish and then only on the last one or two coats use the satin or semi-gloss, this way I can keep the clarity and still achieve the desired sheen. Satin and semi-gloss varnishes are also softer than gloss varnishes because the flattening paste or agent used will soften the film finish. If you need a really hard abrasion resistant finish, but want a satin or semi-gloss sheen, it's best to use a gloss and after it has cured, rub it down with steel wool or other fine abrasives. This will also give you a smoother surface, removing any dust nibs and leveling the surface. What Varnish Should I Use For My Job? To determine what type of varnish you should use for a particular job, you must look at what type of oils and resins are contained within a varnish and what the ratio of oil to resin is. Varnishes that contain a larger amount of oil to resin are called long oil varnishes. Varnishes that contain a lower amount of oil are called medium oil varnishes. Long oil varnishes are more flexible than medium oil, but also softer. Medium oil varnishes are harder, but are more brittle. For exterior use, a long oil varnish is best. Because it is more flexible, the varnish will expand and contract with the wood as changes in temperature and humidity take place. A medium oil varnish will not move as much and therefore as the wood moves and the varnish does not, the varnish will soon start to crack and peel. Medium oil varnishes are best used indoors where a lot of wood movement does not occur and a harder finish is desired. The resin contained in a varnish is also important in determining what type to use for your project. Some resins are more elastic than others, making them best suited for exterior uses. Phenolic resin is more elastic than other resins, therefore it will be able to withstand the extreme wood movement of exterior projects without quickly breaking down and cracking. Alkyd and polyurethanes are better suited for interior use. Not as important, but still a factor is what type of oil is used. Tung oil is more water resistant than linseed or other oils, therefore it would be a better oil for exterior use, but much more expensive. Putting this all together, we basically come down to two categories, interior and exterior use. For exterior use, a modern spar varnish which is long oil and is Wisdom Management Services (M) Sdn. Bhd. 3
  4. 4. Finishing Finishing materials made up of tung oil, Phenolic resins, solvents, dryers an Ultra Violet blockers (to protect the color of the wood from fading) is probably your best choice if you elect to use an oil varnish outside. Although Spar varnishes have a tendency of initially being more amber (yellow) in color because of the color of the Phenolic resin. For interior use, my favorite is polyurethane modified varnish. The best I used is a product called Wood Glo, it is a satin poly that flows out beautifully and lasts decades. It is sold by Constantine's in New York (See Sources) back on my homepage. They also have a gloss version called Super Shield. Wisdom Management Services (M) Sdn. Bhd. 4
  5. 5. Finishing Finishing materials Brushing On Varnish While not very easy to apply by spray application, oil based varnish is one of the easiest finishes to apply by brush. Because varnish sets-up slowly it gives the user plenty of time to brush and spread it out evenly on to the surface. It's hard to spray because it has a tendency to run if applied too heavy. I firmly believe that any film finish can be sprayed successfully if thinned out enough, but varnish is one of the last finishes I would want to spray. Over many years of testing, I have come to realize that brushing is the best way to apply oil based varnish. Before applying varnish by brush, you should know a little more about how long it takes for each coat to set-up and how long before you can apply the next coat along with how it reacts to temperature and humidity and some other facts. Oil based varnish is much higher in solids than some other film finishes like lacquer. Therefore, it should only take a few coats of varnish to build a film significant enough to protect the surface of what you are finishing. After the surface has been sealed, it usually only takes about three coats to give you enough protection. One very important factor when applying varnish is how the temperature effects the speed at which it cures. You should not apply varnish in temperatures lower than 65 degrees. If you apply varnish in lower temperatures it may take several days, even weeks for it to cure. Room Temp. (approx. 70 to 75 degrees) is good for applying varnish. Hotter temps. will make the varnish cure quicker, but the solvent in the varnish will evaporate quicker, making the varnish set-up quickly and you may have a problem getting the varnish to flow out properly. This could result in brush marks, bubbles and an uneven film. When working in temperatures higher than 75 degrees, try not to work on large surfaces. Some Tips For Preparation Try to set aside a room or part of your work shop to apply your varnish. This room should be as dust free as possible. Do not do any other woodworking, (especially sanding) in this area. If you are going to set aside an area of your shop instead of using a different room, it would be a good idea to also surround this area with heavy plastic sheeting. Before applying the varnish, wet mop the floor, this prevents you from kicking up any dust when you walk around. I always place clean craft (brown) paper under the piece I will be varnishing. Once the surface has been prepared properly you are ready to brush on your varnish. Choosing A Brush There are a number of high quality brushes that can be used for brushing on clear topcoats. The best for shellac and lacquers are natural hair (like badger) or china bristle brushes. While any of these brushes will do a great job when Wisdom Management Services (M) Sdn. Bhd. 5
  6. 6. Finishing Finishing materials applying varnish, there is a much less expensive alternative. A polyfoam brush. That's right, the disposable type. Oil based varnish is classified as a cold finish. This means the solvent use is not as strong as evaporative finishes like shellac and lacquer. Alcohol and lacquer thinner will melt a foam brush but the mineral spirits, solvents or turpentine used in most oil based varnishes will not harm a foam brush. Foam brushes are especially useful for novices who have a hard time getting brush marks out when applying a finish. If used properly, you can get excellent results. I always have a good supply of 1",2" and 3" foam brushes in my shop. They are very inexpensive, so I use one for each coat and then throw it away. Wisdom Management Services (M) Sdn. Bhd. 6
  7. 7. Finishing Finishing materials Applying The Varnish Sealer Coats You don't need a special sealer to seal the wood. Special sealers like sanding sealers will not do any better of a job of sealing the wood than the finish itself. Sealers only make the first coat easier to sand, thus speeding up production time. Also, if you use the wrong type of sealer, you may have adhesion problems. The best sealer for your first few coats should be the varnish itself. Take some of the same varnish you are planning to use as your finish and thin it down 50 percent ( this is a 1 to 1 ratio) with mineral spirits or gum turpentine. This will be your sealer. It will do a good job of sealing the wood and you won't have to worry about contamination problems. Pour some varnish through a paper paint strainer or stocking into another can or jar, then add the same amount of mineral spirits into the varnish. Stir well and strain a second time into a deep dish or bowl. It's best to work out of an open bowl or dish so you can easily dip your brush into it. Now, dip the foam brush into the mixture until the brush has been loaded slightly past the bevel on the foam brush. Lift the brush up and let the excess drip back into the dish. Next, brush on the first coat with the grain making sure not to leave any puddles or drips. Allow the sealer coat to dry overnight and then sand with 320 grit paper. Remove the dust with a vacuum, or tack cloth. If you are working on very porous woods, apply a second sealer coat following the previous steps. Varnish Coats It's a good idea to also thin out your coats of varnish a little. You can reduce your varnish 20 to 25 percent 4 parts varnish to 1 part mineral spirits or gum turpentine or 3 parts varnish to 1 mineral spirits or gum turpentine. This will not effect the strength of the varnish, it will only make it flow better and allow time for air bubbles that form when brushing to pop. The only drawback is that you will have to add a few more coats because less will remain on the surface once the varnish has dried. Prepare the varnish by mixing and straining in the same way you prepared the sealer. Use a foam brush and load it in the same manner as the sealer. Apply the varnish to the surface by brushing either with or against the grain initially. The main idea is to get it on the surface doing as little brushing as possible. Once on the surface take one light pass with the tip of the brush moving with the grain. Overlap each pass slightly, then leave the varnish alone, do not do a lot of brushing, this will make the solvent evaporate quicker and the varnish will set up too quickly and not have enough time to flow out. Let the varnish dry overnight, and then sand with 320 grit sandpaper and remove dust using vacuum or tack cloth. When sanding, if the varnish starts to clog the paper, it has not dried enough. If the varnish turns to powder, it is dry enough to sand and apply the next coat. Continue to apply 2 to 3 more coats of varnish using the same process. If you are going to rub out the finish (by wet sanding) after it has cured, you may want to apply at least a total of 6 coats ( not including sealer coats). Wisdom Management Services (M) Sdn. Bhd. 7
  8. 8. Finishing Finishing materials This is because if there is not enough varnish left on the surface, you may cut through the finish into the raw wood in some spots. Once you have applied the last coat, let the finish cure for several weeks before you are ready to use it or rub it out. Varnish does not need much maintenance. If you wish, you may apply a coat of paste wax or liquid polish from time to time. Wisdom Management Services (M) Sdn. Bhd. 8
  9. 9. Finishing Finishing materials ANILINE DYE Water Soluble Information and Application Guidelines: The water soluble anilines are best for light fastness, transparency of colour, accentuating the wood grain, ease of application, lack of lap marks and use under lacquer. They will not leave a muddy surface. They can however raise the grain and create a fuzzy look. Prior to staining lightly sponge the surface with clean water or a dilute solution of dye. Sanding off the raised fibers with fine paper after thorough drying will eliminate this problem. Proper surface preparation is well worth the effort. For best results apply with a sponge, soaking areas thoroughly. Squeeze out the sponge and remove the excess stain, leaving a uniformly damp surface. Let the surfaces dry 12-24 hours before proceeding with polishing or finishing. (It is important to have the depths of the wood dry not just the surface) Hints & Tips: 1 - For consistent results use distilled water & mix powder by weight. 2 - Use plastic straws to pipet (by covering the end with your finger) measured amounts of liquid into a glass container to make small test batches (Keep Notes) then multiply the test batch by an appropriate measure to arrive at a working solution volume. 3 - Remember that the wood tone will show through & blend with the dye colour for your final result. If you are trying to match an existing commercial dyed product, there is a strong possibility that the wood was bleached to remove all colour prior to the dye process; if you hope to replicate the same result, bleach with a two part wood bleach first then dye, you will save hours of frustration. 4 - The water soluble anilines are best for light fastness however different colours are more resistant to fading than others. The following steps are recommended if you wish to assure the best in fade resistance; Use Fresh Solutions, thoroughly saturate the wood with dye 2 or 3 times. Top coat with At Least a sanding sealer, and better, finish coats containing UV (ultraviolet light) inhibitors. TO MIX: Dissolve aproximately (1 oz. in 1 Pint) or (1/4 Lb. in 2 Quarts) or (1/2 Pound in 1 Gallon) of hot (not boiling) water. Add the powder gradually to the water while stirring or agitating. Mix and store in plastic or glass container. For a darker tone, add powder; for a lighter tone use less powder or add water. Cool to room temperature prior to use. Apply using sponge, brush, or cloth. Dye may be mixed, (In its liquid form), to obtain desired colour, shade, or tonal result. Keep notes and make a test on a scrap of the same wood as to be dyed, evaluate colour after wood is dry. LIBERON Van Dyck Crystals (genuine walnut crystals) make an excellent and inexpensive base from which to mix wood tones. STORAGE: It is best to mix what will be used within a short period of time. Store in a dark cool place, tightly capped for up to 6 months. Wisdom Management Services (M) Sdn. Bhd. 9
  10. 10. Finishing Finishing materials ------ KEEP OUT OF THE REACH OF CHILDREN ------ AVOID BREATHING POWDER, and AVOID CONTACT WITH SKIN OR EYES Wash Hands thoroughly with soap and water immediately after use. ANTIDOTE: EXTERNAL, flush thoroughly with fresh water INTERNAL, give magnesia, chalk or whiting followed with emetic (induce vomiting) [Tablespoon of mustard and a Tablespoon of warm water] Call a physician. DO NOT TRANSFER TO UNLABELED BOTTLES OR CONTAINERS WARRANTY: LIBERON Supplies and/or the vendor assume no responsibility expressed or implied, for the results of or the misapplication or misuse of these materials. Wisdom Management Services (M) Sdn. Bhd. 10
  11. 11. Finishing Finishing materials VAN DYCK (Vandyke) CRYSTALS GENUINE WALNUT CRYSTALS To make an inexpensive and useful water stain VAN DYCK CRYSTALS are dissolved in HOT water (not boiling) to obtain colours from dark brown to a light tan. The quantity of crystals can be varied to obtain the desired colour; or make a strong stock solution, then dilute a portion with hot water for lighter tones. To assure even results strain through muslin or clean cotton cloth to eliminate any possible sediment. (The addition of a tablespoon of Technical Ammonium Hydroxide to a quart of solution will increase the penetration into the wood and slightly darken the colour. Keep the ammonia off your hands and avoid breathing the fumes.) (Use water soluble aniline dye in mixed liquid form to enhance or tone towards warm or cool colours.) Always make test for results on a scrap piece of the same wood, or on the under side of a piece of furniture, and evaluate after dry. Wear rubber gloves, and apply with sponge brush or clean cloth. Allow to dry from 12 to 24 hours, depending on atmospheric conditions, before proceeding with your finishing schedule. Water soluble dyes will not bleed into solvent based finishes. Keep notes so the colour may be duplicated in the future. DO NOT TRANSFER TO UNLABELED BOTTLES OR CONTAINERS ------ KEEP OUT OF THE REACH OF CHILDREN ------ Wisdom Management Services (M) Sdn. Bhd. 11
  12. 12. Finishing Finishing materials LIBERON FINISHING OIL 'Too good to be called Danish Oil' Liberon Finishing Oil is a blend of high quality natural oils and resins that can be used to give a smooth, soft sheen to interior or exterior woodwork. Liberon Finishing Oil is very easy to use, has a pleasant low odor formulation and creates an attractive and long lasting finish. One of its components is Tung Oil which is why Finishing Oil has a vary good resistance to water, heat, alcohol and food acid. It is therefore ideal for kitchen and bathroom units, indoor and garden furniture, architectural woodwork, carvings and turned items. During the development of this oil every effort was made to create a product with a maximum "user friendly" factor and Liberon is proud that this oil complies with BS 5665 Part III and is therefore yet another product in our extensive range that is totally safe when used to finish children's toys. DIRECTIONS Shake the container before use. Ensure that the surface to be treated Is both clean and dry. If the work has been previously oiled or waxed, clean thoroughly using Liberon furniture cleaner. Hard finishes such as varnishes or paints must he completely removed using stripper. Any colour alteration to the wood should be done first using water based dye. Brush or rag on a coat of finishing oil, allow 15 minutes for the oil to penetrate and wipe off any excess product with a clean cloth. New wood will require two or three coats which can be quickly achieved as Finishing Oil only requires 3-5 hours to dry depending on conditions. For best results use Liberon Extra Fine Steel Wool to lightly rub down between coats. Although Liberon Finishing Oil is a superb finish in its own right, it is also most suitable as a base for wax finishes and indeed Liberon Black Bison Fine Paste Wax Polish will give the oil finish a deeper sheen. To maintain surfaces finished with Liberon Finishing Oil simply wipe over with a damp cloth or use Black Bison Paste Wax Polish on interior work. Exterior woodwork will require re-oiling once a year. IMPORTANT Always test products first on spare wood or in an inconspicuous place to check compatibility and end results. Wisdom Management Services (M) Sdn. Bhd. 12
  13. 13. Finishing Finishing materials PRECAUTION Do not leave impregnated rags wadded or stacked in bundles. as these can burst into spontaneous fire. Lay them out flat preferably outside, to dry so as to avoid any fire hazard. Available in: 250ml, 500ml, 1 Litre, 5 Litre. Wisdom Management Services (M) Sdn. Bhd. 13
  14. 14. Finishing Finishing materials LACQUER FINISH This column begins a series on individual types of finishes. Since lacquer is the preferred finish throughout the furniture industry, that’s where we’ll start. Let’s begin by understanding a little about the nature of the beast. Lacquer is unlike varnish, polyurethane or paint in one important respect: when it dries, it’s still the same material you had in the can, without the solvents that made it liquid. All the others change chemically as they dry...ordinary lacquer doesn’t. This is important to know because the solvents in the second coat of a lacquer finish will dissolve the first coat...the third coat will affect the previous two, and so on. The more coats you apply, the easier it is to wind up with a mess, and the longer the drying time between coats. This is true whether you’re using a brush-on or spray application. When working in a commercial shop I have taken many pieces with minor scratches and dings and "repaired" them simply by spraying lacquer thinner over the entire piece and then letting it dry. The lacquer thinner dissolved the finish, but did not remove it, letting the scratches be filled in with the now wet (and flowing) finish. This technique is often used by furniture refinishers (with a steady hand) who run up on an "alligatored" or "crackled" lacquer finish. They apply the lacquer thinner to the affected areas with a brush, and let the thinner take care of the marred look. Sometimes an overcoat of new finish is required to complete the job, sometimes not. The same technique, incidentally, can also be used on shellac. It’s a little more difficult to apply, but I suggest the average homeowner use brush-on lacquer unless dealing with a piece (a wicker chair) that just has too many cracks and crevices to get into. Most brush-on lacquers (for home use) don’t require a separate sealer coat. If you’re dealing with an open grain wood you want dead smooth, such as oak or walnut, you may want to use a filler before you do anything else, but that’s another column. If you want, you can use the brush-on for broad flat areas and use an aerosol for details (carvings, turned legs, etc.) as long as you use the same brand. There are differences between brand chemical compositions...don’t ask for trouble. In addition, you’ll get a heavier coat (more protection) with a brush than a spray. Lacquer can be applied over raw wood, shellac, or a sealer made specifically as an undercoat for lacquer. Lacquer will not adhere to any polyurethane or varnish. It will adhere to some paints, but the determining factors are’ll have to tackle that one by trial and error. Read the label on the product you’re considering to find out whether you need a separate sealer. Lacquer is generally used as a clear finish over wood (stained or otherwise) where the grain and color of the wood is meant to show. If you want to hide defects, lacquer isn’t your best choice as a finish, unless you plan to conceal the defect firstt . There are several products on the market that incorporate a stain in Wisdom Management Services (M) Sdn. Bhd. 14
  15. 15. Finishing Finishing materials the lacquer (brush on). Being a traditionalist (old fogey, if you will) I don’t suggest their use except in the lighter shades. As the stain and finish are applied together, it’s very easy to leave streaks in the color, no matter how much you fuss with it. The lighter shades are prone to the same fault, but it’s less noticeable. I strongly suggest staining a piece and applying a finish over that. It’s much easier to control the color and the finish since you don’t have to worry about but one thing at a time. Lacquer is easy to apply, dries quickly, and isn’t too messy cleaning up. On the other hand it’s not as durable as varnish or polyurethane. Wisdom Management Services (M) Sdn. Bhd. 15
  16. 16. Finishing Finishing materials LACQUER FINISHING - Check List SPRAY EQUIPMENT: Make sure your spray gun is set up properly for the material you are spraying & has a matched air cap, fluid nozzle, and needle of appropriate size. LACQUER FINISHING MATERIALS: Thin as little as possible (unless specifically otherwise directed on the label). Over thinning reduces the total solids applied per coat and more coats must be applied to get the same thickness of coating and protection for the surface. Overly thinned lacquer creates many application problems. If flow characteristics need improvement the proper additives should be used to accommodate climatic changes. Spray with as little air pressure as will allow the transfer of material. Too much air pressure causes over atomization resulting excessive air turbulence and overspray. Use high quality thinners and finishing products designed to meet the job requirements. Do NOT Substitute cheap or mismatched thinners or solvents! Use Clear Amber lacquers on medium to dark rich wood tones and for refinishing antiques. Use CLEAR Water White lacquers on very light wood tones and on white or pastel wash stain colors. Use Sanding Sealer usually not more than two coats (even if you are not going to sand). Sanding Sealer seals or primes the wood to provide a base for the build coats and to makes sanding easier. Use Gloss Lacquer after the sanding sealer for the build coats. Using Gloss to build finish thickness as desired, maintains clarity of the finish, and provides superior durability and performance characteristics. Topcoat or finishcoat with: 1 -- the desired sheen (semi-gloss, satin, flatt or dead-flatt) of lacquer if other than gloss sheen is desired. Or Wisdom Management Services (M) Sdn. Bhd. 16
  17. 17. Finishing Finishing materials 2 -- rub the final coat of gloss lacquer to the desired sheen (especially recommended for the tops of antiques and finer work). Use Retarder to solve blushing caused by high humidity or environmental moisture. Blush retarder prolongs drying while allowing the moisture to escape from the applied finish. Use FLASH-OFF CONTROL SOLVENT when conditions are hot, dry and/or windy, to solve orangepeel and roughness from overspray. FLASH-OFF CONTROL SOLVENT will help lacquer flow evenly without delaying the drying time. Use Concentrated Lacquer Tinting Colors to tint or change the color of colored lacquers. Use Sil-Flo to eliminate cratering or fisheyes caused by silicone contamination. Most silicone contamination comes from care products containing silicone; -- Use ONLY silicone free products to care for furniture or fine wood surfaces. PROTECT & MAINTAIN most wood finishes with a furniture & cabinet makers paste wax. Wisdom Management Services (M) Sdn. Bhd. 17
  18. 18. Finishing Finishing materials Lacquer Finishing Problems (Nitrocellulose Lacquers) All information following assumes: A properly matched spray gun needle, nozzle, and spray cap in good working order. Compressor in good working order and drained once or twice daily and pressure regulator controls, and moisture trap installed in the air line as close to the spray gun as possible (within 10 to 25 feet of the gun). ORANGEPEEL: Surface looks like the peel of an orange, or a miniature topographic map. Cause: The film does not level out completely because the lacquer dries before it can flow together.  Corrections: Add Star (TM) FLASH-OFF CONTROL SOLVENT as needed to your lacquer. (Use retarder as a last resort, it will slow your entire finishing and drying schedule.)  Use a matched and proper thinner for your lacquer. Thin not more than 25% unless specified by the manufacturer.  Spray at 8 - 12 inches from the surface.  Use as little air pressure as will allow a proper coat of material to be applied. OVERSPRAY: Roughness or sometimes white looking fuzz stuck in the finish surface.  Cause: Too much air pressure or bounce-back from spraying too close to the surface; or spraying into blind corners and cubby holes, as in bookshelves or desks.  Excessive air flow pre-dries the atomized lacquer before it can reach the surface (such as when spraying outdoors on a windy day).  Corrections: Add Star (TM) FLASH-OFF CONTROL SOLVENT to your lacquer.  Spray at 8 -12 inches from surface. Wisdom Management Services (M) Sdn. Bhd. 18
  19. 19. Finishing Finishing materials  Use as little air pressure as will allow a proper coat of material to be applied.  Spray in an environment free from gusts or excessive air flow. Wisdom Management Services (M) Sdn. Bhd. 19
  20. 20. Finishing Finishing materials FISH-EYES, or CRATERING: Usually round depressions in lacquer, sometimes clear to the wood or substrate,that look like moon craters.  Cause: Contamination in the finish or substrate from silicone and oils.  In refinishing; -- usually from inappropriate wood care products.  Corrections: Clean surfaces thoroughly with naphtha (only a partial help) .  After paint and finish removal or stripping clean surface thoroughly with lacquer thinner or naphtha (only a partial help) .  Add Star (TM) SIL-FLO, as directed on container, to lacquer and sanding sealer.  Maintain wood surfaces with silicone & oil free maintenance products. (Unless it says it is silicone free, you can bet it has silicone in it.)  Keep silicones away from all wood & all woodworking tools and machinery. PIN HOLES: Tiny holes that look like somebody took a pin and put holes in the film of lacquer.  Cause: Moisture in the lacquer when being sprayed.  Corrections: Bleed traps on air lines, bleed compressor tank completely, and make sure air lines are free of moisture on a Daily basis.  Install a moisture trap and a moisture filter as close to the spray gun as possible. GRAININESS: The film looks as if someone threw sand into the lacquer film. Wisdom Management Services (M) Sdn. Bhd. 20
  21. 21. Finishing Finishing materials Cause: * To much air pressure can cause entrapment of air bubbles in the lacquer film. Corrections: * Reduce air pressure; and increase fluid pressure; and reduce film build up. BLISTERS: A raised bubble on surface of lacquer. Cause: Too heavy of a film build-up of lacquer at one time. Corrections: * Cut back fluid and air pressure. * thin down the lacquer (usually not more than 25% unless specifically recommended by the manufacturer). * Spray lighter coats. BUBBLING: Surface looks as if the lacquer boiled and remained grainy. Cause: Lacquer and surface to be sprayed is too hot. Corrections: * Spray lighter coats; * thin down lacquer; * use less air and fluid pressure. Note: When it is over 100o F, it is best to stop and do something else. BLUSHING: Film looks whitish, cloudy, or milky. Causes: * Moisture trapped in the surface of the lacquer from the spray equipment or atmosphere. Wisdom Management Services (M) Sdn. Bhd. 21
  22. 22. Finishing Finishing materials Corrections: * Add BLUSH RETARDER to sanding sealer and lacquer as needed (follow retarder label directions) . * Close doors, - heat rooms, - heat objects being sprayed. * Use air assist hot spray airless for clear lacquers in summer and winter. Summer: * Air pressure to pump should be 40 lbs. air assist should be 20-30 lbs. * To much air pressure to pump and air assist can cause tiny bubbles or gassing along the grain. Winter: * The same as summer except increase pump pressure to 45 lbs., air assist should remain the same. BLOOMING: Film looks bluish, or iridescent. Causes: Undried oil based finishing materials, and/or incompletely cured oil based stains trapped under the surface of the lacquer. Corrections: * Always allow sufficient drying time (for thorough deep drying, not just surface dry or "dry to the touch") of oil based finishing products prior to topcoating with lacquer. * Extend Dry Times of oil based products in cold or humid conditions. * Add Star (TM) BLENCO REDUCER to oil based finishing materials such as oil based stains and pastewood fillers to control drying and accelerate cure times under cool and humid conditions. SAGGING, & RUNS: Runs and drips of lacquer that collect by gravity in thick ridges. Causes: * Over thinning; * Cheap and/or mismatched lacquer thinner; * Cold surface and material; Wisdom Management Services (M) Sdn. Bhd. 22
  23. 23. Finishing Finishing materials * Too much material applied per coat or coats applied in rapid succession; * Worn or damaged spray gun cap, nozzle, and/or needle. Corrections: Remedy or fix any or all of the conditions above in "causes" for sags & runs. POOR ADHESION & New Lacquer Cracking off of corners. First coat flakes off with fingernail and edges or corners chip off easily with minor impact, or bumps. --- Finish lacks durability and rubs, chips, or flakes off easily. Causes: * Dry spray; from too mush air flow as in too much fan speed in a booth or outdoor spraying * Dusty surface or other surface contamination, poorly cleaned or prepared just prior to spraying. * Too much atomization air or too little material leaving the gun. * Spray gun too far away from surface. Corrections: Remedy or fix any or all of the conditions above in "causes" of Poor Adhesion. Wisdom Management Services (M) Sdn. Bhd. 23
  24. 24. Finishing Finishing materials Stain Formulas If you like working with colors and do a great deal of staining or matching stains. The following formulas will help you reproduce various natural wood tones. All the colors are available in many mediums like oil (Japan Colors), acrylic colors and Universal Tinting Colors which can be dissolved in any medium. Stain Formulas. Medium Walnut. 6 parts burnt umber 1/2 part raw umber Dark Walnut 6 parts burnt umber 3 parts van dyke brown American Walnut 8 parts burnt umber 2 parts burnt sienna 1 part van dyke brown Cherry 4 parts burnt sienna 1 part burnt umber 1/2 part French yellow orche Pine 4 parts French yellow orche 2 1/2 parts zinc white 1 part burnt umber Honey Maple Wisdom Management Services (M) Sdn. Bhd. 24
  25. 25. Finishing Finishing materials 6 parts French yellow orche 1 1/2 parts burnt sienna 1/4 part van dyke brown Red Mahogany 5 parts burnt sienna 1 1/2 parts vermilion red 1/2 part van dyke brown Brown Mahogany 6 parts burnt umber 3 parts burnt sienna 1/2 part van dyke brown Golden Oak 5 parts French yellow orche 1 part burnt sienna 1/2 part raw sienna Ebony 9 parts lamp black 1 1/2 parts burnt sienna 1/2 part Prussian blue 1/2 part vermilion red Pickled Pine 6 parts zinc white 1 1/2 parts French yellow orche 1/2 part burnt umber Wisdom Management Services (M) Sdn. Bhd. 25
  26. 26. Finishing Finishing materials Polyurethane finishes: application chart Legend: E=Excellent G=Good NR=Not recommended N/A=Not Applicable Projects Professional Oil-Based Interior Water- Based Interior Oil- Based Outdoor Water- Based Outdoor Oil- Based Floors Water- Based Floors Oil- Based Floors G NR NR NR NR E E Cabinets E E E NR NR G G Shelves E E E NR NR G G Stairs E NR NR NR NR E E Railing E E E NR NR G G Trim E E E NR NR G G Molding E E E NR NR G G Interior Furniture E E E NR NR G G Dining Room Table E E E NR NR G G Interior Doors E E E NR NR G G Interior Crafts E E E NR NR G G Book Case E E E NR NR G G Fireplace Mantle E E E NR NR G G Decorative Accents E E E NR NR G G Interior Windows G G G E E NR NR Exterior Windows NR NR NR E E NR NR Cedar Mailbox NR NR NR E E NR NR Trellis NR NR NR E E NR NR Wisdom Management Services (M) Sdn. Bhd. 26
  27. 27. Finishing Finishing materials Treated Lumber (excluding decks) NR NR NR E E NR NR Exterior Doors NR NR NR E E NR NR Outdoor Furniture NR NR NR E E NR NR Planters NR NR NR E E NR NR Exterior Crafts NR NR NR E E NR NR STEP BY STEP DIRECTIONS Not recommended for: Linoleum, vinyl or glazed tiles and metal. For wood floors, use Varathane Floor Finishes. Previously finished surfaces: For best adhesion, surfaces must be clean, dry and free of old finishes, dust, dirt, oils or other foreign matter. Old finishes in poor condition must be removed. Sand to obtain a smooth surface. Remove all sanding dust using a vacuum or cloth dampened with mineral spirits. Stained or painted wood: Follow manufacturer's direction for application of stain or paint. Make certain surface is thoroughly dry before applying Varathane Premium Polyurethane. Refer to manufacturer's label for dry times. For best results, use Varathane Premium Wood Stains. Unfinished suface preparation: Sand using 150-220 grit sandpaper and remove all sanding dust using a rag dampened with mineral spirits or vacuum. If a filler or putty is used, make sure that it does not contain wax and allow the filler or putty to dry thoroughly. Application tips: Be sure to use adequate ventilation at all times. Apply at temperatures above 55°F and below 90°F. Slower dry times may result from applications on redwood, cedar or woods with a high oil content, use of stain on sealer, or periods of high humidity and/or low temperatures. Use full strength. Wisdom Management Services (M) Sdn. Bhd. 27
  28. 28. Finishing Finishing materials To prevent bubbles in the finish, don't over-brush, shake or apply with a roller. Varathane Premium Polyurethane has a slight amber cast. Test Varathane Premium Polyurethane in an inconspicuous area. Testing is particularly important when applying over paints or stains as the appearance of these products may change slightly when an oil-based finish is applied. Cleanup: For easy cleanup, use paint thinner or mineral spirits. Dispose of properly. For guidance on disposal of unused product, contact your local or state government environment control agency. Coverage: 500-600 square feet per gallon (46-55 square meters per gallon) Legend: E=Excellent G=Good NR=Not recommended N/A=Not Applicable Protects Against: Professional Oil-Based Interior Water- Based Interior Oil- Based Outdoor Water- Based Outdoor Oil- Based Floors Water- Based Floors Oil- Based Scratches E E E G G E E Impact E E E G G E E Scrapes E E E G G E E Sunlight G G G E E E G Salt N/A N/A N/A E E N/A N/A Rain N/A N/A N/A E E N/A N/A Winter Climates N/A N/A N/A E E N/A N/A Water Marks/ Stains N/A N/A N/A E E E E Condensation E E E E E G G Pet Stains E G G N/A N/A E E Heavy Foot Traffic G NR NR N/A N/A E E Tough Household Chemicals E E E N/A N/A E E Color Fading G E G E E E E Wisdom Management Services (M) Sdn. Bhd. 28
  29. 29. Finishing Finishing materials Lightening The Color Of Wood Every day I receive e-mail from people asking my advise on everything from how to repair a damaged piece of veneered furniture to “can I apply a finish to my computer keyboard”. One of the most often asked questions is “ I have a piece of furniture that is too dark and I want to re-stain it to a lighter color, what color stain should I use”? Most people expect me to reply by saying, “no problem, just go out and buy a can of golden oak stain, brush on a couple of coats over the darker color and slap on a coat of polyurethane over the stain. However, many people are surprised by my reply, which is usually “ you need to strip off the existing finish and you probably have to bleach out the all color and apply a new stain. Their reply is usually, “oh no, that sounds like too much work, there has to be an easier way”. Unfortunately, sometimes there is no easy or easier way, and many people do not believe or want to believe what I have told them. It’s just a shame that some of these people go through a lot of wasted work and time just to find out that I was correct and they should have listened to me. There are a number of ways to actually lighten the color of a piece of furniture, but applying a lighter stain over an existing darker color usually does not work. You see all stains are somewhat transparent so the grain of the wood can show through. Some stains, like dyes are so transparent that if you apply a very light color dye to a dark piece of wood, it will actually make the wood darker instead of lighter in the same way a clear lacquer will actually slightly darken a piece of cherry or walnut when it is applied to the surface. Staining will work once in a while depending upon the initial color of the wood (how dark), how lighter you want to make it and if you use a semi-transparent (pigmented stain). Unlike dyes, pigmented stains are not as transparent. In fact, a pigmented stain is actually a thinned down paint. We all know that you can paint over a darker color using a lighter color paint. This is because there is so much pigment in the paint that it blocks out the color you are painting over. A pigmented stain will also block out the color it is being applied over, but not all of it. In order for the lighter pigmented stain to block out all the darker color there would have to be so much pigment in the stain that it would not only block out the darker color but also hide all the grain of the wood, just like a paint. Now, it may start to make sense. If you have a piece that you wish to make slightly lighter and don’t mind giving up some of the wood’s grain that is showing, you could apply a pigmented stain that is slightly lighter than the existing color. When I say slightly, I mean just that. Remember it’s best to apply multiple lighter coats than one thick coat. Once you have achieved the color you desire, let the stain dry very well and then apply a topcoat finish like varnish, lacquer or polyurethane over it to seal. The application of the topcoat may change the color slightly, in any case it’s always best to run a test on a small, inconspicuous spot before attempting to do the whole piece. Wisdom Management Services (M) Sdn. Bhd. 29
  30. 30. Finishing Finishing materials REMEMBER TO RUN THE TEST FROM START TO FINISH (STAIN TO TOPCOAT) BEFORE YOU DO THE WHOLE PIECE, THIS WAY YOU WILL KNOW WHAT TO EXPECT AND IF YOU DO NOT LIKE IT, YOU CAN ALWAYS TOUCH UP THE SMALL TEST SPOT. The best, and sometimes only way to lighten the color involves more time and effort. First, you have to remove (strip off) the existing finish. Usually the best way to do this is to use a paint and varnish remover. If the piece has been built within the last 50 years and the original finish still remains, you may be surprised to find that most or all of the color will come off when you remove the finish. This is because many furniture manufactures added the color right into the finish they used. This was usually lacquer or varnish. Once the finish has been removed, the next step is to wash the whole piece down with mineral spirits. This will remove any traces of the paint and varnish remover that may have been left on the surface. At this point, if you feel the color is light enough, all you need to do is apply a clear topcoat. However, if the color is still too dark or if the wood appears blotchy with lighter and darker spots, your next step is to bleach. Bleaches are highly reactive chemicals that break down the color(s) in the wood. There are basically three types of chemicals most commonly used to bleach wood, Oxalic acid, Sodium hypochlorite and a two part A/B wood bleach. Oxalic acid is a good choice for removing stains in wood, but is very poisonous. Sodium hypochlorite usually works well on aniline dye, but once again is dangerous in inexperienced hands. The two part A/B wood bleach is what I use and the one I suggest you try. It is by far the most effective all around and easiest to use, however, (like any chemical) you must still take great care when using this or any other bleach or wood lightner. NOTE: BLEACH CAN BE VERY DANGEROUS IF NOT HANDLED PROPERLY. FOLLOW THE MANUFACTURE’S INSTRUCTIONS CAREFULLY. NEVER MIX BLEACH WITH ANOTHER CHEMICAL AND ALWAYS WORK WITH A FRESH BATCH. WHEN WORKING WITH BLEACH OR ANY OTHER CHEMICALS, ALWAYS WEAR PROPER SAFETY PROTECTION SUCH AS RUBBER GLOVES, EYE PROTECTION, RESPIRATOR, PROTECT SKIN FROM CONTACT. REFER TO MANUFACTURE’S INSTRUCTIONS FOR SPECIFICATIONS ON PROPER SAFETY PROTECTION. REMEMBER, BLEACH WILL MOST LIKELY REMOVE THE WOOD’S NATURAL COLOR, SO YOU WILL PROBABLY HAVE TO USE SOME TYPE OF STAIN TO GIVE THE WOOD COLOR AFTER THE BLEACHING PROCESS. Applying The Bleach. After the finish has been removed and the whole piece washed down with mineral spirits, let it dry well for a couple days. Using a paint brush, apply a generous, even coat of part A of the two part wood bleach. Let this stand for about 5 or 10 minutes (best to refer to directions for amount of time). Wisdom Management Services (M) Sdn. Bhd. 30
  31. 31. Finishing Finishing materials Don’t worry if the wood starts to look darker, it will lighten up when you apply part B. Next, apply part B in the same manner as you applied part A. The color should gradually start to lighten as the bleach dries. Let the piece sit for at least 4 hours and then wash down with a solution of 50 percent white vinegar and 50 percent water. This will neutralize any chemicals in the bleach left on the wood. Allow to dry at least overnight. Two part wood bleach is usually strong enough to lighten the wood sufficiently in one application, however, if wood needs to be lightened further, repeat the process. Once the piece is dry, you will notice that the grain is very rough. It has been raised by the water in the bleach and the wash down. Next step is to sand down the whole piece with 120 grit paper, then finish sand using 180 or 220 grit paper. Finally, choose a re-stain with color of your choice and finish in manner you wish. Two Part Wood Bleach and other finishing materials can be purchased through Constantine's. 1 800 223 8087 See Sources Back On My Homepage. Wisdom Management Services (M) Sdn. Bhd. 31
  32. 32. Finishing Finishing materials Lacquer Retarder & Flash-Off Control Lacquer Retarder & Blush Control The primary reason for using nitrocellulose lacquers and sanding sealers is that they provide tough, clear protection with a very rapid dry time. Many of the application problems encountered when using these products revolve around this rapid dry and may be eliminated or counteracted by use of LT-5 Lacquer Retarder. Nitrocellulose lacquers and sanding sealers dry by evaporation. This process means that the first dry will occur at the surface; the lacquer will “skin-over”. Under conditions of high humidity water vapor may enter the drying film by the atomizing air from the spray gun or it may condense into the film due to the “chilling” effect the rapidly evaporating solvents have on the ambient air. Cold, damp air will present a greater problem than warm, damp air for this reason. Under conditions of high heat the same surface skin will form very quickly and, possibly, to such an extent that it will be too “thick” to allow the evaporating solvents below to break the surface. “Moisture Blush” will appear variously as a cloudy or milky film; it may have an iridescent “rainbow” sheen, or the film may be flat, regardless of the specified gloss rating. “Heat-bubbling” will appear as many thousands of closely packed bubbles that are so small that they may not be visible to the naked eye. Some of these bubbles may have partially broken the surface to yield a “pebbly” texture and appearance. Both problems will be more severe in those areas of greater coating concentration such as edges and tight moldings. The best method of control for these problems is prevention. Under the conditions mentioned above, when problems are likely, the addition of two fluid ounces of LT-5 Lacquer Retarder per gallon of reduced lacquer will prevent either problem from occurring. In extreme conditions, this ratio may be increased to four fluid ounces per gallon, however, at this level, the drying time will be noticeably slower and may affect production schedules. When moisture blushing or heat bubbling has unexpectedly occurred, one of two methods may be employed to correct the problem. On the piece where more coats of lacquer or sealer are to be applied the addition to the next coat, of four fluid ounces of LT-5 Lacquer Retarder per gallon of coating , as above, will effectively remove the blush or bubbles from the lower coat(s). On pieces where finishing has been completed, a mixture of 75°- LT-3 Lacquer Thinner and 25% LT-5 Lacquer Retarder applied as a “mist coat” will, likewise, eliminate the problem. The above mixtures may also be used to abate minor orangepeeling problems. Wisdom Management Services (M) Sdn. Bhd. 32
  33. 33. Finishing Finishing materials DO NOT use more than 6 fluid Oz. per gallon of reduced lacquer. The 75-25 solvent retarder mixture above is also available in aerosol as Blush Eliminator or Blush Eraser. Flash-Off Control & Orangepeel or Overspray The use of IBIB (aka Flash Off Control Solvent) will eliminate orangepeel and overspray problems. Flash Off Control Solvent should be the additive of choice when conditions are warm, dry, and drafty. IBIB allows the lacquer to flow by retarding the flash or set point. Its use will not delay drying or production. When moisture blush is evident in humid conditions retarder is required (see above). DO NOT use more than 6 fluid Oz. per gallon of reduced lacquer. Wisdom Management Services (M) Sdn. Bhd. 33
  34. 34. Finishing Finishing materials Bar and Table Top Nitrocellulose Lacquer SPRAY Finishing Schedule for KITCHEN CABINET, Bath Cabinet and where resistance to moisture or humidity is desired Remove ALL hardware from ALL surfaces receiving finish ! All coats shall cover all drawer and door surfaces including all edges and back sides. Backs (surfaces against walls etc.) and cavities for built in appliances shall have 1 sealer coat and 2 coats of lacquer. Surfaces adjacent to appliances shall be finished as though exposed. If drawers are self-pull (without hardware pulls) edges and back surfaces shall be finished as faces. Applied wood drawer fronts will be removed and the backs finished as faces. Apply all lacquer with Conversion HVLP or Conventional spray equipment. Note: all coats are to be applied as even wet coats, not flooded on, nor fog misted. NO orange peel is allowed. Add Star Flash Off Control solvent to effect flow if required by spraying conditions. Use lacquer Retarder to control moisture blushing only. Do Not over thin finishing coats or the film build will not be enough to provide moisture protection. Always make a test panel to check adhesion and color. Evaluate color with all finish coats in place. Each layer of lacquer will slightly change and add to the final color. For a Premium Finish: Optional Prep Step: (for darker or medium toned woods requiring a light finish) Use a two step Wood Bleach (sometimes necessary for very light tone finishes) For Stained Wood: Optional Prep Step: - Apply STAR Bleachtone (color mask) to create an even toned base for stain. (The Bleachtone mask will help achieve an even stain color tone.) NOTE: To minimize growth patterns or the grain in the wood Use STAR # 94 Seal and Stain, or a washcoat, (1:1 Lac. sanding sealer and Lac. Thinner), prior to staining. Apply a pigment wiping stain of the desired color by spray or brush and wipe off excess to desired effect. A pigmented stain is preferred in cabinet Wisdom Management Services (M) Sdn. Bhd. 34
  35. 35. Finishing Finishing materials work where hardwood and plywood exist side by side. An even color effect is easier to achieve with a wiping stain. It is more difficult to achieve an even tone between ply and hardwood with dye stains. Most dyes (especially red and reddish tones) Do Not have the same light fastness or fade resistance to sunlight as the same color of pigmented stain. Dyes do have a place in some finishes to help give an even color to the overall background. Dyes can also darken light woods for a deeper color tone where a wiping stain alone will not yield a deep enough tone. NOTE: dye stains are always used on bare wood. Some dye stain products will enhance or emphasize any wood growth patterns making these areas in the wood stand out and look darker. Nitrocellulose Lacquer Sprayed Finishing schedule for Kitchen Cabinets #1 --- APPLY Sanding Sealer, thinned no more than 20%. It is very important that the first coat be applied wet enough to effect a proper bond and adhesion to the substrate fiber. Lack of adhesion and subsequent faking or de-lamination of the entire finish coat from the substrate can occur if this coat is "fogged" on too dry and does not flow and wet the substrate. Sand (#180 Sterate Coated Paper) and LIBERON #00 Steel Wool to remove gross or obvious roughness. (For the best resistance to moisture, use vinyl sanding Sealer & for better durability a PreCat Sealer & Lacquer should be used) #2 --- APPLY 2nd coat of Sanding Sealer, thinned no more than 20%. This coat is especially important on softer woods to provide an even base for the build coats. Sand #220 Sterate Coated) and LIBERON #0000 Steel Wool to remove ALL nibs or roughness. -- Optional: Apply glazing here if desired to enhance the moulding or finish color texture. #3 --- APPLY GLOSS Lacquer, thin as little as possible, not more than 20%. Use Gloss for all build coats for durability, toughness, and to maintain clarity. #4 --- APPLY 2nd coat of GLOSS Lacquer, thin as little as possible. For a Minimum Cabinet Finish eliminate step #4 & 5 and go To #6 #5 --- APPLY 3rd coat of GLOSS Lacquer, thin as little as possible. For a Standard Cabinet Finish eliminate step #5 and go To #6. #6 --- Sand (#220 Sterate Coated) and Steel Wool #0000 to remove all nibs or roughness. Wisdom Management Services (M) Sdn. Bhd. 35
  36. 36. Finishing Finishing materials #7 --- APPLY Desired Sheen of Lacquer (Satin, Semi-Gloss, or Gloss) thinned as little as possible, not more than 20%. NOTE: A lacquer toner can be added to the sanding sealer or any of the lacquer build coats to enhance or adjust the finish color. If this is done prior to the last 2 coats minor scratches in the surface won't remove color. For honey amber to darker tones use Clear Lacquer (actually slightly amber). For very light wood tones use Water White (clear as water) Lacquer. If a non- yellowing finish is important such as on a whitewash or very light pastel stains use Cab-Acrylic Lacquer or our 9000 series waterborn Lacquers. Evaluation of the "KITCHEN Cabinet" Finish: Do not be fooled by looks! If you finish only to a finish that looks good, has an even sheen, and smooth throughout, you probably Will Not have enough finish on the surface to provide long term durability required of such finishes. The Clear Build coats of finish (Steps #4 above) provide the film thickness that can stand up to high frequency of use, abrasion and the continued cleaning typical in such environments. Nitrocellulose Lacquer Advantages: Quick drying. Can be applied in a wide range of climatic conditions. Easy to Repair or Recoat. Can be applied over a wide range of stains and dyes. For commercial work and the best durability a Conversion Varnish finish is suggested. Wisdom Management Services (M) Sdn. Bhd. 36
  37. 37. Finishing Finishing materials POLYURETHANE Let’s talk about what is probably the most widely used (by homeowners) furniture finish today...polyurethane. It has many of the advantages of varnish, with few of the drawbacks. Polyurethane dries more quickly than varnish, so you don’t have to worry (as much) about dust settling in the wet finish. It flows better than varnish, so brush marks are more likely to disappear. Correctly applied, polyurethane is more durable than varnish. Many people, however, won’t use it...why? The most common complaint against polyurethane is that it "looks like plastic". Well, the chemical structure (when dry) is very close to plastic, but the reason some people get that idea is from being told that a certain piece of furniture, such as a restaurant table top, is coated with polyurethane, when in fact, it isn’t. Since they don’t like the way the top looks, and they’ve been told it was polyurethane, they don’t like polyurethane. Most of the ultra-thick finishes you see on commercial furniture (furniture exposed to the public on a regular basis) is a plastic, which strangely enough is why it looks like plastic. If you take three identical pieces of furniture, finish one in lacquer, one in varnish, and one in polyurethane, no one is going to be able to tell you which is which without testing the finish with solvents. One other complaint against polyurethane (mainly from people like me who work on furniture finishes) is that polyurethane is very difficult to repair, and many times difficult to remove when stripping furniture. Well it can be repaired and it can be stripped, so that bias just reveals how lazy (I admit it) some repairmen are! Polyurethane lends itself to good results with a minimum of investment. It’s its own sealer, and you don’t need a fancy brush to get good results. Foam brushes give great results. Of course you can’t use the brush but one time, but if you’re going to put three coats on a piece of furniture, you won’t need but three brushes at, say eighty-nine cents each? That’s a lot cheaper than a fifteen or twenty dollar brush, which you have to clean after every use. Remember I’m talking about the home owner...not the professional. The professional will invest in the good brush, and keep it clean, because it’s cheaper in the long run. But for the do-it-yourself who’s going to do one or two pieces of furniture in a year, shelling out twenty dollars for a brush is ridiculous. As with varnish, work with a small area (about one foot square) and then move on, overlapping as you go. Brush from wet to dry. In other words, brush from the wet area of finish toward areas yet to be covered. On table tops, do the edges first and then work from the middle of the top out to the edges. Never start a brush stroke at the edge moving’ll drag finish off the brush and it will run Wisdom Management Services (M) Sdn. Bhd. 37
  38. 38. Finishing Finishing materials over the edge. Again as with varnish, don’t over brush. Get it on the surface, smooth it out, and leave it alone. The few brush marks you leave will settle out if you don’t keep messing with it. When finishing turned legs, work around the leg, starting at the top and working down. When finishing square ( unturned legs) work from top to bottom on all four sides at once. Do the edges of flat surfaces first, then work from the middle of the surface out to the edge. Polyurethane is a modern, durable finish that is easily applied by the beginner, producing and wear resistant finish in a variety of sheens, from matte to gloss. As always, read the instructions on the can carefully. The manufacturer knows more about his product than you do...and they want you to have good results. Wisdom Management Services (M) Sdn. Bhd. 38
  39. 39. Finishing Finishing materials SHELLAC – A TRADITIONAL FINISH STILL YIELDS SUPERB RESULTS by Jeff Jewitt To the average person, shellac probably invokes many negative perceptions. Poor water and heat resistance, difficult to apply, poor drying and low durability are all criticisms that I hear when I mention shellac to my clients or other woodworkers. While some of these criticisms are valid, many are not grounded in fact and are easy to disprove. Other negative aspects are overcome by using proper tools, techniques, and most important -- proper product. To experienced finishers and restorers of fine furniture the world over, shellac remains the finish of choice. One of the most elegant finishes for furniture, French Polish, is done with shellac. Conservators and restorers of antiques use shellac for re-finishing antiques. And most importantly, its low toxicity makes it a perfect choice for items that come into contact with food or children's toys. There are countless other advantages to using shellac that are listed in at the end of the article. But as with every finish option available, there are disadvantages and these are listed also. HISTORY Most people have no idea of what shellac is or where it comes from. Shellac is a natural, organic resin that comes from an insect, Laccifera lacca, that is about the size of an apple seed. This bug alights on certain trees indigenous to India and Thailand and during its reproductive cycle feeds on the sap that it sucks from the twigs of these trees. The bug secretes an amber colored resinous substance that is called "lac", a word that comes from the Sanskrit "lakh" which means one- hundred thousand. The resin forms a cocoon around the insect which serves to incubate the eggs she lays. This cocoon is the raw material for shellac and is called "sticklac", because it contains resin, parts of the twig and bug remains. The sticklac is washed and then refined either chemically or by hand, to produce the raw material available for sale to commerce. The original cultivation of shellac was not for the resin, but rather, for the dye that gives the resin its characteristic color. The use of lac dye can be traced back to 250 AD when it was mentioned by Claudius Aelianus, a Roman writer in a volume on natural history. The lac dye was removed by the initial washing of the shellac resin in large kettles, which is also the first step in preparing the resin. This dye remained a valuable commodity until the mid-1800's, when Perkins, an English chemist, synthesized the first chemical 'aniline' dyes which killed the natural dye industry. Fortunately the use of the resin had been firmly established, so the loss of the use of the dye had little impact on shellac trade. The first use of shellac as a protective coating appears as early as 1590 in a work by an English writer who was sent to India to observe the country and its people. Commenting Wisdom Management Services (M) Sdn. Bhd. 39
  40. 40. Finishing Finishing materials on a procedure for applying lac to wood still on the lathe he writes "they take a peece of Lac of what colour they will, and as they turne it when it commeth to his fashion they spread the Lac upon the whole peece of woode which presently, with the heat of the turning (melteth the waxe) so that it entreth into the crestes and cleaveth unto it, about the thicknesse of a man's naile: then they burnish it (over) with a broad straw or dry Rushes so (cunningly) that all the woode is covered withall, and it shineth like glasse, most pleasant to behold, and continueth as long as the woode being well looked unto: in this sort they cover all kinde of household stuffe in India".* ( It's interesting that many woodturners still finish this same way today.) * From "Shellac; its production, manufacture, chemistry analysis, commerce and uses." London, Sir I. Pitman & Sons, ltd., 1935 pg. 3. The use of shellac as a furniture finish never caught on in the West until the early 1800's and it eventually replaced wax and oil finishes. It remained the most widely used protective finish for wood until the 1920's and 30's when it was replaced by nitrocellulose lacquer. SHELLACS OTHER USES The most fascinating uses of shellac have nothing to do with finishes. Because of its specific characteristics, it has a wide variety of uses, most of which continue to this day. According to the Zinsser Company, which is the largest supplier of shellac in this country, the top four uses for the dry shellac flakes are pharmaceutical, confectionery, hats, and food coatings, in order from highest to lowest. Protective coatings for wood ranks about number eight. Pharmaceutical - shellac is used to coat enteric pills so that they do not dissolve in the stomach, but in the lower intestine, which alleviates upset stomachs. Its also used as a coating on pills to "time release" medication. Confectionery - shellac is used to provide protective candy coatings or glazes on candies like Reese's Pieces, because of its unique ability to provide a high gloss in relatively thin coatings (like a French Polish). It was used at one time on M&M's. It is approved by the FDA as a food safe coating when dissolved in pure ethanol (not denatured). Hats - shellac is used to stiffen felt used to make hats. It allows the makers to shape the felt into brims, bowl shapes, etc. Food Coatings - because of its FDA approval, shellac is used to coat apples and other fruits to make them shinier. Electrical – shellac mixed with marble dust is used by lamp manufacturers to glue the metal base to glass incandescent bulbs. Wisdom Management Services (M) Sdn. Bhd. 40
  41. 41. Finishing Finishing materials Other uses for shellac are in the manufacture of grinding wheels (it allows the abrasive particles to break off at the low heat generated by the grinding process, thus exposing new, fresh abrasive particles), leather finishing and painting (shellac pigmented with white titanium dioxide is widely used by painters as a stain sealer, wallboard primer, and knot and sap sealer on wood). Other former uses for shellac are electrical insulators, as a glue (it bonds glass and metal surprisingly well), phonograph records (the old 78's were a mixture of shellac, fillers and lampblack), hair spray, no-rub floor polishes, and as a finish for bowling alleys (the weight of the ball dropping on the shellac surface did crack the finish). The demise of shellac's many uses was brought about by the emergence of more durable synthetic resins such as Bakelite, cellulose nitrate, acrylics and urethanes. However, as mentioned above, it still finds a wide variety of applications in our society. It's interesting to note that many attempts in the early part of this century were made to duplicate the shellac resin. Despite the attempts by scientists to duplicate shellac synthetically, a little Indian bug still makes it best. THE MANY VARIETIES OF SHELLAC Most woodworkers think of shellac as a liquid bought at a paint store. What many do not realize is that shellac is traded and sold as dry flakes. Those who have used shellac from a paint store probably used a type known as #1 Orange, which is the most commonly traded flake used as a wood finish. This is but one of the many grades of shellac available and it is dissolved in ethanol which is the most widely used solvent for shellac. The many varieties of shellac resin differ primarily in color as well as properties. The type of tree, climate conditions, the region where harvested, and the time of year harvested all play a role in determining the different colors and grades of shellac. The most expensive varieties of shellac are Kusmi and Golden Bysacki and these are chemically refined to extract adulterants such as rosin and wax into golden pale flakes sold under a variety of names like Behlen's "Super-Blonde" or Kusmi Superior or Bysacki Golden. When dissolved in ethanol, these flakes produce a very transparent gold finish. The least expensive grade of shellac is traded as TN which stands for "truly native" in this country. This type of shellac is processed from the raw sticklac by hand in India. Other grades of shellac which can be considered intermediates are #1 Lemon or Lemon-Orange all of which naturally contain wax. Some suppliers sell unrefined forms of shellac known as Buttonlac or Seedlac. These grades need to be strained after dissolving in ethanol to remove foreign matter. Seedlac is also further refined by bleaching and wax removal to produce the white-shellac sometimes still sold in paint stores. The dry flake form of this product is called "bone-dry" shellac flake and is Wisdom Management Services (M) Sdn. Bhd. 41
  42. 42. Finishing Finishing materials widely used in applications where the natural orange color of shellac would be undesirable (such as hats). The shellac industry grades shellac by many variables, but the two most common are wax content and color. The most expensive shellacs, Kusmi and Bysacki, have virtually no wax content (less than 1%) and a high color number 70-80. The lower grades of shellac -- TN, orange lemon and buttonlac -- have a wax content from 3%-5 % and color numbers of 20 or lower. Mail-order companies that sell dry shellac flakes classify it according to color (pale, dark, white, Super-blonde) and sometimes by grade (#1 Orange, Button- lac, Seedlac, etc.). Other characteristics to consider is whether it has been de- waxed. Dewaxed shellacs have much better transparency and moisture resistance. (The wax in the shellac reduces the clarity of the finish and also reduces the molecular weight of the shellac resin, making it less resistant to water). On the downside, dewaxed shellacs have a much shorter shelf life after mixing with alcohol (less than 6 months). DRY vs. DISSOLVED SHELLAC Once the dry flakes are dissolved in ethanol, a chemical process known as esterification begins. What happens is that the alcohol starts to chemically modify the hard shellac resins and ultimately turns them into a sticky gum which doesn't dry. This is responsible for one of the most often heard complaints about shellac -- that it won't dry. Large manufacturers such as Zinsser have started to label their cans with a shelf life date (three years), but for the best results and working properties, you achieve better results if you prepare your own shellac from dry flakes. Dry shellac flakes store indefinitely under proper conditions, but contrary to what you may hear, it won't store forever. Given enough time, especially under hot, wet conditions, dry shellac reacts with itself to form polymers that are insoluble in alcohol. Shellacs that have been dewaxed are more prone to this. You can extend the usable life of dry shellac flakes by storing them after purchase in a cool, dry area -- a refrigerator is best. A test for suspected old shellac is easy -- simply dissolve the flakes in alcohol. Most shellacs should be totally dissolved within three days. If you see a gelatinous mass after this time, the shellac is past its usable life and should be discarded (don’t confuse natural wax with this). If you just purchased it, return it to the company you bought it from. Sometimes in summer months, shellac will cake together. This is known in the industry as "blocking" and is not a sign of bad shellac. Break up the shellac with a hammer and dissolve it in alcohol as usual. Wisdom Management Services (M) Sdn. Bhd. 42
  43. 43. Finishing Finishing materials Dissolve dry shellac flakes in denatured ethanol, which is sold in most paint stores. It also dissolves in methanol, butyl and propyl alcohol. Methanol will evaporate the quickest, followed by ethanol, butyl and propyl alcohol. The last two alcohols, butyl and propyl can be added to shellac dissolved in ethanol in small amounts to act as retarders, which make the shellac stay wet longer for better application (like brushing). Lacquer retarder can also be used. I do not recommend using methanol as a solvent because it is very toxic. In some older finishing books, methanol is referred to as wood alcohol or methylated spirits, but its use is discouraged. Once dissolved in alcohol, shellac eventually esterifies as mentioned above. Although I have successfully used 12 month old shellac, shellacs older than 6 months should be tested. Pour a small amount onto a piece of glass. If not dry to the touch within 5 minutes, it should be discarded. For this reason, it's a good idea to make up only enough shellac to use within a six-month period. MAKING THE CUT The ratio of dry shellac flakes dissolved in alcohol is known as the cut. It refers to the amount in pounds of dry shellac flakes dissolved in 1 gallon of alcohol. A 3 lb. cut would be 3 pounds of shellac dissolved in 1 gallon of alcohol. A 1 lb. cut would be 1 pound of shellac dissolved in a gallon an so on. Since a gallon is a large amount for mosr finishing tasks, you can factor down the ration to suit your needs. For example ¼ lb flakes dissolved in 1 pint of alcohol will yield a 2 lb. cut. It’s best to weigh the shellac flakes – small inexpensive food portion scales calibrated in ounces are available at houseware supply stores. USING SHELLAC There are many advantages to using shellac. Low toxicity, ease of application, and ease of repair are the best reasons to use shellac. Yet, like any finish, there are some disadvantages which are mentioned below. However, some of the reasons people cite as the disadvantages of shellac are based on misconceptions. Two of the most common ones can be easily explained. The first is that it won't dry. This problem can be avoided by using freshly dissolved shellac flakes. The second complaint against shellac is poor moisture resistance. This can be overcome by using dewaxed shellac and fresh product. Using old shellac solution will decrease its moisture resistance. You can easily prove this. Take a board that has been finished with fresh shellac and after it has fully dried (about a week), pour some water on the finish and let it sit overnight. When you come back the next morning you will still see the puddle of water, but the finish will be only slightly marred. Shellacs ability to withstand water decreases with the age of the film, so don't try this on old finishes. An interesting feature of shellac is that it resists water-vapor very well. In tests done by the United States Forest Products Laboratory on the moisture-excluding Wisdom Management Services (M) Sdn. Bhd. 43
  44. 44. Finishing Finishing materials effectiveness of wood finishes (the ability of a finish to prevent moisture vapor from entering the cellular structure of the wood – called MEE), shellac rated above polyurethane, alkyd and phenolic varnish and cellulose-nitrate based lacquers. ADVANTAGES 1. Non-yellowing when compared to varnish and cellulose-nitrate based lacquers. 2. Quick-drying. Many shellacked items can used the same day or shortly thereafter. 3. Wide variety of colors available. 4. Superior adhesion -- no other type finish can surpass it. 5. Excellent hardness -- it can be sanded and rubbed out well. 6. Excellent as a sealer coat to raise the fibers of the wood for subsequent sanding. Also seals in finishing contaminants such as silicone, waxes, dirt and oils. 7. Ease of repair. Because shellac re-dissolves in alcohol, scratches and other minor surface imperfections can be invisibly repaired by re-applying shellac to the damaged area. The new shellac melts into the old shellac allowing for perfect repair work. 8. Ease of removal. Old and new shellac can be removed with denatured alcohol which eliminates the need for harmful and toxic strippers. 9. Can be wiped on (padded), brushed or sprayed -- all with good results. 10. FDA approved -- safe for food utensils and children's toys. 11. No unpleasant or toxic fumes. DISADVANTAGES 1. It re-dissolves in alcohol so perfumes and strong alcoholic beverages like whiskey will mar the surface. Wisdom Management Services (M) Sdn. Bhd. 44
  45. 45. Finishing Finishing materials 2. Forms white rings on contact with water. This is more of a problem with shellacs that have wax and old shellac surfaces. 3. Tendency to show scratches. The resistance to scratches can be improved by a simple waxing. 4. Has a shelf life after mixed in alcohol. 5. Not resistant to alkaline compounds. Alkaline chemicals such as lye and ammonia discolors and mars shellac because of its acidic composition. These chemicals are frequently found in household cleaning products. 6. Sensitivity to heat -- shellac starts to soften at about 150 degrees F. Hot items can mar the surface. Keep in mind that some of the disadvantages, like scratching and marring with alkalis, are easily repaired because of one of shellac's great advantages -- its ease of repair. APPLYING SHELLAC Shellac can be applied by practically any method -- brushing, padding, or spraying. My favorite method is padding, which many woodworkers may not have heard of. This technique takes advantage of shellac's rapid drying and allows the finisher to apply a finish in a much shorter time than varnish, polyurethane or oil finishes. It works best on flat surfaces, and in a nutshell, here's how it's done. Use a 2 lb. cut shellac and some padding cloth, which is available from finishing suppliers as trace cloth or French polishing cloth. It should be as lint-free as possible. Do not use cotton T-shirt type cloth or cheesecloth. Cut a piece of cloth roughly 10"-12" square. Fold it up into a pad so that there are no creases on the bottom. Pour about 1 ounce of alcohol on the cloth and work the alcohol into the cloth. Then take a squirt bottle of shellac and dispense approximately one ounce of shellac into the pad. Starting at the top of the board, bring the pad down on the surface like an airplane coming in for a landing, then lift it slowly off the board at the edge like taking off. Repeat this motion in stripes down the board. When you get to the bottom, the shellac that you put on the top will be dry enough to wipe again. Keep doing this until the surface is tacky and the pad starts to stick. Between wipes, pad the edges. The trick to this is to apply light coats of shellac by keeping the pad moist, not dripping wet. (If you can squeeze shellac from the pad it's too wet). When finished with padding, store the pad in a jar with a tight cap and re-use it. If this is the first application on new Wisdom Management Services (M) Sdn. Bhd. 45
  46. 46. Finishing Finishing materials wood, the shellac should penetrate quickly and be dry enough to scuff-sand with 320 stearated sandpaper to remove the raised fibers in about an hour. Repeat the same process as above until the pad starts to stick. Let this application dry overnight and then scuff sand with 320 grit stearated sandpaper and then steel wool with maroon synthetic steel wool or 000 regular steel-wool. Repeat the padding application one more time and let it dry overnight. Then rub the finish out with 0000 steel wool, using wax thinned with mineral spirits as a lubricant. After the wax dries to a haze, wipe the excess wax off with a soft cotton cloth. This leaves a very mellow, hand-rubbed satin finish. This padding technique can also be used on sides, legs aprons and drawers, provided they are relatively flat, but on complex surfaces I like to use a brush. A brush can also be used on the flat surfaces as described below. BRUSHING SHELLAC Brushing shellac is very different from brushing oil-based finishes such as varnish or polyurethane. Part of the difficulty is that because shellac dries so fast you can't come back later with a brush and even it out. It takes some practice but the following pointers should help. The best brushes for shellac are those that hold a lot of finish which allows you to flow it out on the board rather than brushing it. The brush that performs the best for flowing on finish is a fitch brush. Fitch brushes used to be pure skunk hair, but some have soft badger hair on the outside to produce a smooth finish and a center of skunk hair to give the brush body. Most sold nowadays are very fine, soft china bristle dyed to resemble badger-hair. If you've never used an expensive brush before, you'll quickly realize that it's worth the price. My second choice for a shellac brush would be pure white china bristle. Before brushing, dip the brush all the way to the ferrule( the metal part near the handle) into alcohol and then wring it out. This makes the brush easier to clean later. I like to use a 1-1/2 lb. cut shellac solution for brushing. Take one part of the concentrated solution prepared above and add 4 equal parts alcohol. This light cut minimizes brush marks which are hard to rub out later. Dip the brush about halfway into the 1-1/2 lb. cut solution and bring the brush out and let the excess shellac run off, then drag it lightly across the top of the jar or can your using. Starting about 2" in from the edge, drag the brush lightly to the edge, then come back all the way to the other edge. Brush once and quickly come back to even out the finish if it's uneven, but don't work it too much. Brushing shellac doesn't create air bubbles so these should not be a problem. Brush another coat next to the previous one, slightly overlapping it by about a 1/4 inch. Work down the board until it's covered and then do the edges. After the shellac is dry, (1 hour for the first coat, overnight for subsequent coats), scuff sand and steel wool like the Wisdom Management Services (M) Sdn. Bhd. 46
  47. 47. Finishing Finishing materials padding schedule above. Three coats should be sufficient for close-grained woods like cherry or maple, but you may want 4-5 coats on open-pored woods like mahogany. Rub the finish out with wax and steel-wool as above. To clean brushes, you do not need to use expensive alcohol solvents. Household ammonia cleans shellac brushes because the alkaline ammonia dissolves the acidic shellac. Washing the brush with soap (I use Dawn dish-washing detergent) and water afterwards keeps the bristles soft. REPAIRS TO SHELLAC FINISHES Over time, shellac finishes can show surface scratches and other minor mishaps like water rings. These are very easy to repair with alcohol, the solvent for shellac. Surface scratches can be repaired easily by flowing in a thin cut of shellac (1 lb.) into the scratch. Use a very fine artist's brush like a #1 or #2. If the scratch has gone through the finish and the stain, you can mix the shellac with alcohol soluble dyes or pigments to match to original color. White water spots can be treated the same way, but usually only with straight alcohol. Padding or brushing a coat of shellac and then rubbing it out like above restores the finish so that it looks even. If you're not sure whether the original finish is shellac, a simple test will confirm this. Dab some alcohol on an inconspicuous area such as behind a leg. If the finish gets tacky, it's shellac. If you're not confident in your abilities for the above repair techniques, a simple cleaning with mineral spirits or naphtha, followed by a light coat of paste wax improves the look of the finish quite a bit. Wisdom Management Services (M) Sdn. Bhd. 47
  48. 48. Finishing Finishing materials USING WOOD BLEACH TYPES OF BLEACHES There are three general classification of bleaches used on wood; peroxide or "two-part" bleaches, chlorine bleach and oxalic acid. Each type will work on some colors and not on others. The trick in using any bleach is selecting the correct one for the stain. Knowing beforehand what made the stain in the first place will help in selecting the correct bleach. Peroxide Bleaches These bleaches are sold as two-part or A/B bleaches. The two components are usually sodium hydroxide and strong hydrogen peroxide. Used by themselves they are ineffective but when mixed together, a strong oxidizing reaction is formed which is most effective in removing the natural color in wood. To a lesser degree they will lighten some pigment stains, but are ineffective on dye stains. Chlorine Bleaches Chlorine is a strong oxidizer that will remove or lighten most dye stains. A weak chlorine based bleach such as Clorox will work but generally takes too many applications to be effective. A much stronger solution can be made from swimming pool bleach, which is a dry chemical called calcium hypochlorite. It is inexpensive and can be purchased from a pool supplies retailer. Oxalic Acid Oxalic acid is unique in that it will remove a certain type of stain formed when iron and moisture come into contact with tannic acid in the wood. Some woods like oak, cherry and mahogany naturally contain a high amount of tannic acid and a black stain is formed when the wood gets wet with tap water (tap water contains iron as a trace mineral). A wet glass or leaky vase left on these woods will produce a black ring. Nails and screws will form black rings around the head if the wood gets wet. If tap water is used to wet unfinished oak and mahogany, small gray spots may form on the surface of the wood. Oxalic acid will remove this discoloration without affecting the natural color of the wood. Wisdom Management Services (M) Sdn. Bhd. 48
  49. 49. Finishing Finishing materials Oxalic acid is also used to lighten the graying effects of outdoor exposure. It is the ingredient in most deck "brighteners". Used on furniture that has been stripped for re-finishing, it will lighten the color and re-establish an even tone to the wood, particularly oak. USING BLEACHES Ideally, a bleach should be selective in its removal of color. What this means is that it should only remove the color that you want and not the color of anything around it. The guide below should provide a starting point, but in most cases you'll need to experiment, particularly if you do not know the composition of the stain in the first place. Since most bleaches are poisonous and/or caustics, wear the appropriate gloves, dust mask (if mixing dry bleach powders) and chemical safety glasses. Lightening Wood Removing the natural color of wood is best done with the two-part peroxide bleaches. These are available as "A/B" bleaches sold in most paint and hardware stores. The most common way to apply this product is to wet the wood thoroughly with part A (sodium hydroxide) then immediately apply part B (hydrogen peroxide). It's important that part A not sit too long before applying part B because sodium hydroxide will darken some tannin-rich woods like cherry and oak. You can also mix the two parts together and apply them at the same time, as long as you do it as quickly as possible after the two parts are mixed. Usually one application is all that's necessary, but another application may be needed to even out the bleaching effect. Some dark woods, like ebony, are not affected by this bleach which is an advantage if you want to bleach a wood that has ebony stringing. On some woods, particularly walnut, a greenish tinge may appear in some areas if the bleach is not applied evenly. To alleviate this problem, try to apply the bleach evenly and sparingly, just enough to make the wood wet. Do not flood the wood with bleach. Neutralize the alkaline effect of this bleach after the wood is dry by applying a weak acid like vinegar. Use white vinegar mixed one part vinegar to two parts water. A/B bleach will remove all the natural color variations present in wood, so use them judiciously. Over - bleached woods will lack tonal variations and depth even if stained afterward. I use them only when matching sun-faded wood, or to provide a neutral base upon which I create a decorative finish like pickled oak or blond mahogany. When re-creating the fruitwood finish on bleached cherry explained above, I had to hand glaze selective areas during the finishing process to provide some color variation. A/B bleaches can be used to compensate for Wisdom Management Services (M) Sdn. Bhd. 49
  50. 50. Finishing Finishing materials heartwood/sapwood variations, but I prefer to bring the sapwood in line with the heartwood by hand coloring or spraying the sapwood with a dye stain. Color Removal Chlorine bleaches are best used for removing dye-based stains. The chief advantage of this bleach is that it will remove or lighten the dye without affecting the natural color of the wood. To use this type of bleach, purchase dry calcium hypochlorite from a swimming pool supplier and mix a saturated solution of the powder in hot water. A saturated solution is formed by adding the powder to the water until no more powder will dissolve. The mixture will start to foam a little and loses its effectiveness if stored, so I only make up what I'll use right away. Apply the solution liberally to the wood and in some cases, the dye will immediately disappear. Other dyes may take a while to bleach and some may only lighten. Wait overnight to determine the full bleaching effect. If the color hasn't changed after two applications, applying more bleach will be ineffective and you'll need to try an alternate technique. Chlorine dyes are usually ineffective on pigment based stains. The only way to remove these are by sanding or scraping. Stain Removal If you can determine the composition of the stain you can remove it with the correct bleach. Iron based stains are fairly easy to spot. They are grayish-black and usually ring shaped. It may also show up as a splotchy appearance on oak that has been stripped. Before applying the oxalic acid remove the finish first. Mix a saturated solution from dry crystals in hot water and apply to the entire surface, not just the stain. Several applications may be needed with overnight drying in between. Once dry, it's imperative that any residual oxalic acid be removed from the surface of the wood before sanding or finishing. Several rinses with distilled water will remove most of the oxalic acid crystals left on the wood surface. Neutralize the acidic wood surface with a solution made from one quart water with two heaping tablespoons of baking soda. Stains that form on wood during the drying process are varied in their composition. Sticker stain, brown stain, streaking and light "ghost" stains are all common problems and some can be removed by bleach. The composition of the stain may be chemical or microbial, so trial and error is needed when attempting to remove these stains. I start with oxalic acid, then chlorine. Lastly A/B bleach can be tried, but since removal or acceptable lightening of the stain results in bleaching of the surrounding wood, this is a last resort. Remember that some stains do not react to use of a bleach, so if two applications of a bleach are ineffective, move on to another bleach. BE SURE TO NEUTRALIZE EACH Wisdom Management Services (M) Sdn. Bhd. 50
  51. 51. Finishing Finishing materials BLEACH AFTER USING BY RINSING WITH PLENTY OF DISTILLED WATER--- RESIDUAL BLEACH CAN REACT WITH ANOTHER - GIVING OFF NASTY VAPORS. Stains from foods like grape juice, tea or fruits can be removed with a chlorine bleach. Wipe the whole surface so that you get an even effect. Some blue and black inks based upon iron can be removed with oxalic acid, but carbon based inks like India ink cannot be removed by any bleach. CREATIVE USES FOR BLEACHES Sometimes bleaching is the first step in certain finishing processes. In creating certain special effects like blond mahogany, pickling and pearlized finishes bleaching is done to establish a neutral or consistent undertone to the wood surface. Bleaching is also the first step in matching old wood that has changed color from exposure to light. A/B bleach is used in all the effects. Blond Mahogany - Use A/B bleach to remove the natural red from the wood. When dry, sand lightly to knock down the grain then apply a dark mustard colored pigment stain (like nutmeg or fruitwood) and wipe all the excess off. This produces a light yellow-brown color that was a popular finish in the forties and early fifties. Bone - Apply A/B bleach and when dry, lightly sand. Then apply a white pickling stain or you can make your own from thinned oil paint. A pure white stain will result in a bone white effect that is a little "antiseptic". Addition of a small amount of raw umber tint to the white stain adds a cool, "bone" effect. Pearlized - Follow the directions for the Pickling above, but after one coat of clear finish, lay some rags lightly dampened with an extremely dilute purple alcohol or NGR dye on the surface momentarily. Crumple the rags so that a spotted effect is achieved. The dye may attack some finishes like lacquer so be careful. Seal this color in with another clear coat of finish then do the same procedure using an extremely dilute red dye. Seal this with clear finish. Water clear lacquers like acrylic or CAB lacquers work best for this effect. Avoid amber colored lacquers and varnishes. Wisdom Management Services (M) Sdn. Bhd. 51
  52. 52. Finishing Finishing materials Matching old wood - Apply A/B bleach and when dry scuff sand. Then apply a dye to establish the final color of the wood. For sun-faded walnut and mahogany, an amber/honey color dye will work. For woods that change to a very different color, like teak, use a light brown dye tinted with a bit of orange. Wisdom Management Services (M) Sdn. Bhd. 52