The binder is the film - forming component of paint which is also called vehicle. This is the only component which has to be included in paint. There are other components that are added optionally according to the properties of the cured film. Binders include synthetic or natural resins such as alkyds, acrylics, vinyl-acrylics, vinyl acetate/ethylene (VAE), polyurethanes, polyesters, melamine resins, epoxy, or oils. They can be categorized according to the mechanisms for drying or curing.
Binders can be categorized according to the mechanisms for drying or curing. Although drying may refer to evaporation of the solvent or thinner, it usually refers to oxidative cross-linking of the binders and is indistinguishable from curing. Some paints are formed by solvent evaporation only, but most rely on cross-linking processes. Paints that dry by solvent evaporation and contain the solid binder dissolved in a solvent are known as lacquers. A solid film will be formed when the solvent evoperates and lacquers are unsuitable for applications where chemical resistance is importance because the film can re-dissolve in solvet.
Diluent or solvent:
The main purpose of diluents are to dissolve the polymer and adjust the viscosity of the paint. It is volatile and does not become an integral part of the paint film. It also controls the flow and application properties.In some cases, it can affect the stability of the paint if its in a liquid state. Its main function is as the carrier for the non volatile components.
This component is optional as some paints do not have any diluent. Water is the main diluent for water-borne paints and the co-solvent types.
Pigment or filler:
Pigments are granular solids incorporated in the paint to contribute color. Fillers are granular solids incorporate to impart toughness, texture, give the paint special properties, or to reduce the cost of the paint. Some paints contain dyes instead of pigments or used in combination with pigments such as an alternation. Pigments can be classified as either natural or synthetic. Natural pigments include various clays, calcium carbonate, mica, silicas, and talcs. Synthetics would include engineered molecules, calcined clays, blanc fixe, precipitated calcium carbonate, and synthetic pyrogenic silicas. Fillers are a special type of pigment that serve to thicken the film, support its structure and increase the volume of the paint.
Apart from the three main categories of ingredients, paint can have a wide variety of miscellaneous components, which are usually added in small amounts, yet provide a significant effect on the product.