Mask, Masking. A protective covering, either solid (as a jig), or liquid (as a stop-off lacquer), which is used to protect a portion of a metallic surface for a temporary period of time while some operation is being applied to the unprotected surface. Often used in the finishing department for a variety of techniques, including: partial platings, multicoloring techniques or mixed media finishes; this occurs where two or more treatments are required on one surface of a medallic item. Afterwards the mask is removed or stripped off exposing the protected surface. See finish and finishing, jib, partial plating, stop-off lacquer.