With the notable exception of high acid value aciylics, where basic pigments should be avoided, in order to prevent viscosity instability or premature gelation, pigmentation does not pose special problems in formulating paints based on thermosetting acrylic resins.
For white paints, rutile grades of titanium dioxide are incorporated at pigment/binder ratios from 0.6/1 for automotive finishes, where very high gloss levels and DOI’s (Distinctiveness of Image) are required, to 1.3/1 for metal decorating enamels where opacity is of prime concern.
High quality inorganic and organic coloured pigments are widely used in formulating thermosetting acrylic paints. They should be selected on the basis of fastness to organic solvents, such as aromatic hydrocarbons, esters or ketones, and heat resistance.
As will be seen later, one of the most important applications for thermosetting acrylics is in automotive finishing, where colour fastness and durability are extremely important.