The quest to produce environmentally friendly and low-toxicity coatings has generated many new types of coatings and modifications to existing systems. One broad (if slightly artificial) classification we could apply is that of 'free coatings': coatings which are almost or entirely free of some major ingredient that would normally have been thought of as an indispensable part of the resin or formulation.
Under this classification scheme, a discussion of VOC-free coatings does not include those which are intrinsically VOC-free such as dry films, solventless epoxies or powder coatings; even though their environmental benefits are just as real, they are confined to particular niches, and the main interest in environmental terms lies in eliminating VOCs where it appears most difficult to do so.
A remarkable number of such coatings types now exist, and there is only space to discuss some of the most interesting or unusual of them below. Alkyl phenyl ethoxylates (APEOs) were at one time very widely used as surfactants in emulsion coatings.