Paints, Varnishes and Lacquers –Composition, Types and Availability
Paint is a semi-solid fluid which, on application to a surface in a thin layer is converted into an opaque, solid film. Paints are available in many colours, though the commonly used one is white.
Paints and enamels
The basic components of paint are:
PIGMENT: This contributes the color to the paint. It also serves to increase the opacity and the thickness of the paint. Pigments may be:
- natural, such as calcium carbonate
- synthetic, such as calcined clays
- hiding which make the paint opaque, such as titanium dioxide.
BINDER/CARRIER/VEHICLE: This is the main component which imparts adhesiveness to the paint and helps it to stick to the surface permanently. Resins, whether natural or synthetic, are the popularly used binders.
SOLVENT: This is added to the paint to adjust the viscosity and the density of the paint to enable easier spreading. The solvent also aids in the initial drying process of the paint. Water is the commonly used solvent in water-based paints while alcohol and turpentine is used for oil-based ones; stronger solvents like ketones and esters may sometimes be used for industrial or commercial purposes.
In addition to the above three, the below components are available in most modern paints.
FILLERS: These are special type of pigments that give the required thickness to the film. This helps the paint to harden on drying and also serve to increase the total volume of the paint. Mica, silica and clay are the popularly used fillers.
ADDITIVES: This is a general term used to indicate any substances added in small amounts to help in preserving the paint and improving the finished appearance. Common additives are manganese, cobalt, some silicone based compounds etc. In commercial paint, additives are also used to give gloss or matte finish. However, including additives in paint may lead to increasing the drying rate of the paint. The additives used in many paints can be any of the below classes of substances.
- Dryers: to accelerate the drying process of the paint.
- Stabilizers: to help in the efficient storage of the paint. These can be anti-settling agents to reduce the sedimentation of the pigment particles or anti-skinning agents to prevent a tough layer to be formed on the paint surface during storage.
- Anti foaming: to prevent foaming of water-based paints during application.
- Anti-marring: to improve resistance to scratching.
- Anti-mould: to reduce any mould growth on paints in cold conditions
Classification of paints
The whole plethora of paints can be broadly classified into oil-based paints and water-based paints.
♦ Oil-based paints or oxidative drying paints
Oil-based paints are primarily those where the pigment particles are suspended in some kind of drying oil, like linseed oil. They are toxic and highly flammable. It takes a longer time to dry or, in painting terminology, cure after an application. The drying process involves a chemical reaction between the oil in the paint and the oxygen in the air; hence they are also called oxidative drying paints. Oil paints usually give a hard and glossy finish and are considered to be resistant to wear-and-tear.
Examples are Enamel paints (oil-based enamels) and Alkyd paints. Both of these paints use alkyd resin.
♦ Water-based paints or physically drying paints
Water based paints consists an emulsion of a polymer (resin). They are non-flammable and non-toxic paints which dry (or cure) quickly due to the evaporation of the solvent. Latex paints are the most common type of water-based paints used for home as well as commercial purposes. Latex paints used to have rubber resin as the binding agent. But today, they have synthetic polymers like acrylic or vinyl resins as binders depending on which the paint is named as acrylic or vinyl paint. Water-based acrylic paints are also referred to as emulsion paints.
Latex paints can be flat, semi gloss or glossy.
Difference between Latex paint and Enamels (Oil based ones)
The main distinguishing features between oil-based enamels and water-based latex paints can be listed as follows:
--Enamels, being oil-based, give lots of fumes and a strong odor while Latex paints do not.
-- Enamels are expensive, but last a lifetime. Latex paints are comparatively cheaper, but easily damage or crack.
-- Enamel paints dry slowly and give a more glossy finish. Latex paints dry fast but do not produce as much gloss.
While most of the enamels are oil-based paints, water-based enamels have been recently launched by Asian Paints Ltd. Hence, today enamel mainly refers to any hard and glossy finish.
What are distempers?
Distempers are water-based paints which have glue as the binder. The major constituents of distemper paints are chalk and lime, besides water and water-soluble colors. They are mainly applied to the interiors.
A Varnish is a colourless, transparent fluid which gives a hard protective finish. It is popularly used on wooden surfaces, though it is also suited on other materials.
All varnishes are composed of the following constituents:
DRYING OIL: This serves as a binding agent in varnishes and helps to increase the durability of the varnish. The most common oil is the linseed oil.
SOLVENT (THINNER) : Thinner reduces the consistency of the oil-resin mixture. Turpentine is the widely used thinner.
RESIN: Resin may be of natural origin like gum, copal and pine or synthetic such as polyurethanes and vinyl.
Turpentine is used as a thinner in paints and varishes
Varnishes are primarily distinguished as per the type of resin. For instance a polyurethane varnish is one which has a polyurethane resin. A shellac varnish is one which has lac as the varnish; the solvent in this case is ethanol.
Varnish finishes are usually glossy, but may also be made to produce a satin or semi gloss finish by addition of flattening agents.
Lacquers are special types of varnishes which dry by solvent evaporation, and can therefore cure quickly. It basically consists of a resin - mainly synthetic - which is dissolved in a fast-drying solvent like naphtha or toluene.
Many lacquer varnishes are generally sprayed on the surface, instead of brushing, such as those used in spray guns or aerosols to paint automobiles and cars. With addtives, these are sometimes referred to as lacquer paints.
Lacquer painting a car.
Though varnishes and lacquers are used interchangeably the main difference is that lacquers dry only by solvent evaporation while varnishes dry by the process of oxidation.
The Leaders in Today’s Paint and Varnish Industry
There are numerous brands of paints and varnishes available in the marker. Popular among them are:
- Asian Paints
- Berger Paints
- Jenson & Nicholson
- Nerolac Paints
- British Paints
- ICI Delux
- Nippon Paints
- Gem Paints
- Mayur Paints
- Sheenlac Paints
Many of the above companies, like Asian Paints Pvt Ltd and Jenson&Nicholson produce varnishes and lacquers too.
According to a recent report, the Indian Paint industry is a Rs. 49 billion sector, with Asian Paints India Pvt Ltd. (APIL) having an overall marker share of 33% in the organised paint market.