mudeli pinnale sukeldamise teel vedelvormisegusse moodustunud koorik (kate) täppisvalus; mudelile kantakse mitu koorikut mille tulemusena moodustub mitmekihiline valuvorm (vt täppisvalu), in investment casting, an extremely fine ceramic coating applied as a slurry to the surface of the pattern to reproduce maximum surface smoothness; the first precoat is followed by other coats of different viscosity and usually containing different grading of ceramic particles (see: investment casting)