Session 2: Paint Ingredients, Classification, and Quality
What is Paint?
Paint is a colored or clear, liquid or solid substance that, when applied to a surface and exposed to heat, certain chemicals, or air, converts to a dry, coherent, and adherent film offering protection to the underlying substrate. Paint consists essentially of three main ingredients:
Paint Ingredients
1. Resin:
Also called binder, medium, film former, or vehicle. This is the most important and main liquid part of the coating and consists of a sticky, viscous (thick), manmade or natural substance which gives the coating:
- Adhesion to the substrate (makes the paint stick)
- Durability – resistance to abrasion, water, chemicals, UV rays, heat, etc. (makes the paint last long)
- Flexibility – to move with the expanding underlying substrate
- Gloss – to make the paint shiny and more washable
2. Solvent:
This is a clear, volatile substance that readily evaporates on exposure to the atmosphere and thus forms no part of the dried coating. It is used to give the paint:
- Ease of application by thinning the viscosity of the resin or paint
- Penetration on substrates of low porosity
- Assistance during manufacturing by thinning down the thick resin and wetting dry powder
- Modification of paint physical properties such as drying, smell, gloss, etc.
The combination of resin and solvent forms a clear coating or varnish.
3. Pigment:
This is the main solid part of the coating and consists of one or more fine, colored powders. Two kinds of pigments are used in paints:
- Quality paints use more high-grade hiding pigments such as titanium dioxide along with small amounts of other pigments to provide the color.
- Lesser quality paints use more of different types of pigments (called extenders or fillers) such as talc, clay, silica, calcium carbonate, etc., along with less quantity of colored pigments. While these may provide good hiding capabilities, they lack durability and wear quickly.
Pigments provide:
- The desired color.
- Opacity (the ability to hide or cover the underlying substrate).
- Increased protection (high build, corrosion resistance, etc).
- Texture (e.g., eggshell or matt finish).
Additives:
To the three main ingredients, many other substances may be added in very small quantities (called additives) to enhance or suppress specific qualities of certain paints, e.g., anti-foaming agents, biocides, thickeners, driers, etc.
Paint Classification
It is very difficult to classify or group the wide variety of paints available for decorative use.
1. Classification by solvent used:
- Water-Based: Thinned with water, dry rapidly, relatively cheaper, better smell, thicker, and heavier compared to oil-based paints. Mainly used on concrete, plaster, asbestos, etc.
- Oil-Based: Thinned with various thinners (mostly white spirit), dry more slowly, relatively more expensive, stronger smell, generally thinner and lighter than water-based paints. Mainly used on wood, metal, plastics, etc.
- Solventless: These paints have no solvent, are made and used without diluting, and dry after stoving, heating, or subjecting to some form of radiation. Examples include powder paints (used for fridges, electric cookers), glass coatings used on metallic bathtubs, and Thermoline road-marking paint.
2. Other Classifications:
i. Colour – e.g., white, light colours, dark/deep colours, clear
ii. Finish/Texture – e.g., gloss, eggshell, matt, rough, smooth, textured
iii. Market segment – e.g., decorative, industrial, automotive, marine
iv. Number of components – e.g., single pack, 2K (2-pack)
v. End-use – e.g., road-marking, swimming pool, floor, roof
vi. Resin used – e.g., alkyd, epoxy, chlorinated rubber, PVA
vii. Method of application – e.g., brush, roller, spray, dipping
viii. Method of drying – e.g., air-dry, stoving, catalyzed, UV-cured
ix. Use in the system – e.g., primer, sealer, undercoat, topcoat
It is very difficult to say which of these classifications is best since each one is more useful in one situation or another.
Paint Quality
What makes good quality paint?
Painting is an investment in product, time, and labour, so it is important to choose high-quality paint with a long-lasting finish. If you take the time to select high-quality paint at the start, you will reap the benefits for many years to come.
High-quality paints provide complete coverage with fewer coats on any surface. With high durability, they withstand more wear and tear, scrubbing, and washing than lower-quality paints—saving you time in labour and money in product. Other paint grades with names like Professional, Architectural, or General Purpose will work but will not perform as well as true premium-quality paints.
Premium paints are made with more and better ingredients, making them easier to apply, look better, and last longer. They contain both the best pigments and binders, plus a higher proportion of these solids (the components that remain after drying). Economy paints may provide initial hiding by using extenders, but these lose their hiding power and colour over time—particularly when exposed to weather.
Almost all high-quality paints offer one or more unique features such as:
- Extended durability
- Low/zero VOCs
- Washability
- Ultra-smooth finish
- One-coat hide
- Superior touch-up
- Mar resistance
- Low odour
Some Myths about Paint Quality
Myth 1: Oil-based paints are better than water-based paints because they are more washable.
Not necessarily.
Today, water-based paints can match and even out-perform traditional oil-based coatings. With environmental concerns, manufacturers are focusing on low-VOC products. Water-based paints offer low VOCs, easy cleanup with water, quick-drying, alkali resistance, and stable, non-yellowing colour over time. Some, like vinyl matt emulsions, are now formulated to be highly washable and can even be used on metals.
Oil-based paints do have some advantages such as attractive gloss, good levelling (brush strokes smooth out), and a hard, durable finish. But they yellow in dark areas (e.g., cupboards) and are prone to alkali attack on plaster and concrete.
Myth 2: Thick paint is necessarily better than thin paint.
No.
Paint can be made thick simply by adding thickener, without extra resin or pigment. Diluting thick paint lets you cover a larger area but reduces opacity (requiring more coats) and durability (since there is less resin per litre for protection).
Myth 3: An expensive paint is not necessarily better than a cheaper one.
Within the same manufacturer, expensive paints are usually better.
Manufacturers charge more for premium paints because they contain higher quantities of better-quality ingredients. Price is therefore a good indicator of quality within one brand. However, between different brands, price can be misleading, some companies charge more simply because they are market leaders.
Myth 4: There is no real benefit in using good quality paint.
Definitely false.
Premium-quality paint saves you time and money. For example, painting once every five years instead of every two years reduces labour costs, product use, and inconvenience. Premium paints may also require fewer coats, lowering labour charges further.