the presentation that is about the chemical composition, properties method of application and importance of varnishes used

1. Name = Junaid Asghar
Class no = 148
Section = E.

2. Varnishes:
• It is a more or less transprent
liquids,which are used to
provide a protective surface
coating like paint.

3. Varnishes:
• It is a more or less transprent
liquids,which are used to
provide a protective surface
coating like paint.

4. Advantages
• At the same time varnishes allow the orignal
surface to show and add a lustrous and glossy
finish to it.
• Finishing wood with varnish not only
preserves it but it also protect it against
scratches and strians.
• It also beautifies wood pieces.

5. Types of Varnishes
A)Natural resin varnishes:
• Body made from natural resin obtained from certain trees.
• Natural resin obtained from living trees or from
fossils(which are superior)
• Vehicle in varnish are linseed oil,soya bean oil,fishoil etc
• Resins dissolved in oil ►mixture heated to temperature
(500-600OF) depending on the amount of gloss required
• Oil and natural resin varnish ►OLEORESINOUS varnish
• Thinners are turpentine oil
• Dryers used in varnish are organic salts of iron,zinc, to
accelerate the oxidation and hardening of vehicle

6. B) Modified natural-resin varnishes:

7. C) Synthetic- resin varnish:
• Synthetic varnish produced by plastic
industry
• Chemicals used include nitrocellulose,
amino resins, silicon etc
• Vehicle most often the same as for
oleoresinous varnish
• Coal tar derivatives may be used as
thinners
• Dryer is also the same as for other types
of varnishes

8. CLASSIFICATION OF VARNISHES
• a) LONG-OIL VARNISH:
• Long oil contain 40 to 100 gal of oil per 100 lbs of
resin
• Takes longer time to dry
• Moderate gloss
• Marine and spar varnish belongs to this group
• Tung oil used ► impervious to water

9. b) MEDIUM-OIL VARNISH
• Medium-oil contain 12 to 40 gal of oil per 100 lbs
of resin
• They dry faster ► harder
• Harder film than long-oil varnish but are not
impervious to water
• Floor varnish belongs to this group

10. c) SHORT-OIL VARNISH:
• Short-oil contain 5 to 12 gal of oil per 100 lbs of
resin
• Dry rapidly ► form a hard film that withstand
much rough usage
• Polishing varnish belongs to this group

11. Suitable Enviornment for appling
Varnish:
• Choose well lit area.
• Choose a ventilated area.
• Choose an area that is free from dust and dirt.
• Pay attention to the temperature(21-26 c) and
humidity

12. Preparing materials for varnish:
• Remove the old finish.
• Remove the old by sand paper or by other
methods.
• Remove the dust particles,
• Clean it with a damp cloth and leave it for
drying.

13. Varnishing the materials:
• Prepare the varnish for the initial coat.
• Apply the first coat and let it to dry.
• Clean the first coat with a damp cloth and let
it dry.
• Apply the second coat and let dry, and so on.
• Wait for the varnish to finish curing.

14. Product Information:
• Coverage =12-14 m^2/lit/coat.
• Thinner = Mineral turpentine oil.
• No of coats = 2-3 coats.
• Cleaning = clean all equipment with
turpentine oil.