What is Varnish and Types of Varnishes

Definition

Varnishes are more or less transparent liquids which are used to provide a protective surface coating in much the same way as paints do” At the same time they allow the original surface to show but add a lustrous and glossy finish to it. All varnishes have basically the same components as paints.

What is Varnish? Varnish is a transparent, hard, protective finish or film primarily used in wood finishing but also for other materials. Varnish is traditionally a combination of a drying oil, a resin, and a thinner or solvent. Varnish finishes are usually glossy but may be designed to produce satin or semi-gloss sheens by the addition of "flatting" agents.

Types of Varnishes

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 is the same as used in oil-based paint. Resins dissolved in oil ► mixture heated to temperature (500-600OF) depending on the amount of gloss required. Oil and natural resin varnish ► OLEO RESINOUS varnish. Thinner and dryers used in varnish are the same as used in oil based paints

Modified natural-resin varnishes:

Made from natural resin ► altered by chemical action. Common resin is heat treated with glycerin to form a gum. This gum is treated as the body for the varnish. Less expensive varnish than the oleo resinous varnish

Synthetic resin varnish:

• Synthetic varnish produced by plastic industry
• Chemicals used include nitrocellulose, amino resins, silicon etc
• Vehicle most often the same as for oleo resinous varnish
• Coal tar derivatives may be used as thinners
• Dryer is also the same as for other types of varnishes

Classification of Varnishes

1. 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

2. 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

3. Short oil resins:

Short-oil contain 5 to 12 gal of oil per 100 lbs of resin. Dry rapidly ► form a hard, brittle film that withstand much rough usage. Polishing varnish belongs to this group

How to Varnish

Varnish Finish

Floor Varnish

Oil Varnish

Plasters

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Distempers

They are paints used for the treatment of masonry walls. Water instead of oil is used as a vehicle ► known as water-paint too. Powdered white chalk and glue boiled in water are mixed. Usually colored by mixing different pigments. All Distempers mixed with water only before being used. Distemper affected by weathering condition and takes off if washed ► to be used only in interior works. Cheap, durable and easy interior finish. Should be applied on clean and dry surface.