Coating means a material applied to a substrate for decorative, protective, or functional purposes. For the purposes of this subpart, coatings include paints, porcelain enamels, sealants, caulks, inks, adhesives, and maskants. Decorative, protective, or functional materials that consist only of protective oils, acids, bases, or any combination of these substances are not considered coatings for the purposes of this subpart.
40 CFR § 63.4181
Terms used in this subpart are defined in the CAA, in 40 CFR 63.2, the General Provisions of this part, and in this section as follows: