Varnishing is done to protect and beautify wooden surfaces. An ideal varnish forms a hard, durable protective film while maintaining an attractive gloss. Varnishes contain resins like copal or shellac, driers to accelerate drying, and solvents like linseed oil, turpentine or spirits of wine. Main types are oil, spirit, turpentine and water varnishes, which vary in drying time and durability. The varnishing process involves preparing the wood surface, treating knots, applying multiple thin coats until finished.

1. SNJV432@GMAIL.COM
PART-VIII

2. CONTENT
• WHAT IS VARNISH
• WHY VARNISHING IS DONE
• CHARACTERISTICS OF AN IDEAL VARNISH
• INGREDIENTS OF A VARNISH
• TYPES OF VARNISHES
• PROCESS OF VERNISHING

3. WHAT IS VARNISH

4. WHY VARNISHING IS DONE
• To intensify or brighten the appearance of natural grain in wood.
• To render brilliancy to the painted surface.
• Varnishes can be used to protect wooden surfaces like windows,
doors, floors and roof trusses from atmosphere.
• To protect the painted surface from the atmospheric action.

5. CHARACTERISTICS OF AN
IDEAL VARNISH
• It should render the surface glossy.
• It should dry rapidly and present a finished surface which is uniform
in nature and pleasing the appearance.
• The colour of varnish should not fade away when the surface is
exposed to the atmospheric action.
• The protecting film developed by varnish should be tough, hard, and
durable.
• It should not shrink or show the cracks after drying.

6. INGREDIENTS OF A VARNISH
• Resins
• Driers
• Solvents

7. RESINS
• The commonly used resins are copal, lac, or shellac and rosin.
• The copal is a hard substance and is available from the earth at place
where pine tress existed in past . It is available in variety of form.
• The lac or shellac is obtained by exudation of some types of insects in
India.
• The rosin is obtained from the pine tress.

8. DRIERS
• The function of driers in varnish is to accelerate the process of drying .
• The common driers used in varnishes are white copper and lead
acetate.

9. SOLVENTS
• Depending upon the nature of resins, the type of solvent is decided .
Solvents Resins
Boiled linseed oil Amber, Copal
Methylated spirits of wine Lac or Shellac
Turpentine Mastic , Gum dammar,
Rosin
Wood naphtha Cheap varieties of resins

10. TYPES OF VARNISHES
• Oil varnishes
• Spirit varnishes
• Turpentine varnishes
• Water varnishes

11. OIL VARNISHES
• The linseed oil is used as solvent in this type of varnish.
• The hard resins such as amber and copal are dissolved in linseed oil
and if the varnish is not workable, a small quantity of turpentine is
added.
• The oil varnishes dry slowly, but they from hard and durable surface.
• They are used on coaches and fittings in houses.

12. SPIRIT VARNISHES
• The methylated spirits of wine are used as solvents in the type of
varnish.
• The resins are of soft variety such as lac.
• The spirit varnishes dry quickly.
• But they are not durable and are easily affected by weathering action.
• They are generally used for furniture.

13. TURPENTINE VARNISHES
• The turpentine is used as solvent in this type of varnish.
• The resins adopted are of soft variety such as gum dammar, mastic
and rosin.
• There varnishes dry quickly and possess light colours.
• They are not durable.

14. WATER VARNISHES
• The shellac is dissolved in hot water and enough quantity of either
ammonia or borax or potash.
• There varnish are used for varnishing maps, picture, etc.
• They ae also used for delicate internal works and as covering for wall
paper.

15. PROCESS OF VERNISHING
• Preparation of surface:-The woodwork is thoroughly rubbed down
by means of sand paper. The surface is then made smooth and clean.
• Knotting:-The process of knotting is then carried out as in case of
painting.
• Stopping:-This is done by means of hot weak glue size.
• Coats of varnish:-The varnish is then applied on the surface in thin
coats. The next coat is applied after the previous one has thoroughly
dried up.