Constituents of Paints
The range of substrates to which paints are supplied differ markedly not
only in their physical and chemical characteristics but also in the severity
of the service environment to which a painted surface is to be exposed.
This requires a multiplicity of paint materials that are used to coat a
very wide variety of surfaces. Despite the apparent complexity of substrates
that require coating, all paints are basically similar in composition
in that they contain a suspension of finely ground solids (pigments)
in a liquid medium (vehicle) consisting of a polymeric or resinous material
(binder) and a volatile solvent. During the drying of paint, the
binder forms a continuous film with the necessary attributes of adhesion,
flexibility, toughness, and durability to the substrate (the surface
being coated).
Paints also contain additives, which are added in small quantities to
modify some properties of the pigments and binder constituents.
The wordpaintsis sometimes used broadly torefer to all types of organic coatings. However,by definition a paint is a dispersion of a pigmentor pigments in drying oil vehicle. Theyfind little use these days as industrial finishes.Their principal use is for primers. Paints dryby oxidation at room temperature. Comparedto enamels and lacquers their drying rate isslow; they are relatively soft and tend to chalkwith age.
