materials that form the undercoats of paint and varnish coverings. The principal purpose of the prime coats is to provide durable adhesion between the outer (covering) layers and the surface being painted. In addition, they may perform other functions, including the protection of metal from corrosion, the enhancing of wood grains, and the covering of pores and other defects of the surface being painted. Prime coats are made from natural or synthetic, liquid or solid film-forming substances—drying oils and al-kyd. urea-formaldehyde, and epoxy resins. The hard film-forming materials are used in the form of concentrated solutions and dispersions in organic solvents or water. Many prime coats contain pigments (iron oxide, red lead, or zinc chromate) and sometimes fillers (talc, mica, or chalk).
Prime coats are applied with a putty knife or by spraying. The thickness of prime coats is 10–100 microns (0.01-0. 1 mm). Dried prime-coated surface is covered by paint or lacquer.
REFERENCESBeliaeva. K. P., T. V. Todorova, and N. G. Shtan’ko. Lakokra-sochnye materialy dlia otdelki izdelii iz dereva. Moscow, 1971.
Spravochnik po lakokrasochnym pokrytiiam, 2nd ed. Edited by M. M. Goldberg. Moscow. 1974.