Лако-красочные материалы — производство

This testing is in addition to the high temperature testing described previously. High temperature masking tape can be applied to a variety of surfaces—plain, primed, or painted; metal, glass, rubber or chrome finished—and testing must include them all. The simplest test is to apply the tape to the appropriate surface, subject it to the heat and for the time period that the tape can expect in practical use, then strip the tape from the surface at various rates, both immediately, while the panel is still hot, and after 1 h, when the panel has been allowed to return to ambient temperature, visually examining the surface for any signs of cohesive failure.

Masking tapes, however must conform to curves, and the adhesive must hold at high temperatures under these stressed states. Also, it is common practice to use paper or plastic drapes to cover other areas which may accidentally receive the applied paint. These drapes or ‘‘aprons’’ are set into place by the same masking tape and quite often adhered to the backing of masking tape already applied directly to the surface to be painted. Using a high velocity, high temperature oven samples of the masking tape under evaluation should be set in the oven at the evaluation temperature in a manner duplicating this use: that is, in curves of various radii and applied to its own backing in similar curves, with apron paper attached, both in slight and excessive curves, and to its own backing. These test panels should be mounted vertically in a manner such that they are under the effect of the high velocity hot air. After the test cycle, the samples are carefully examined for signs of lifting. All of the previous tests can be duplicated to include applying the various paints that the masking tape may encounter in use, then investigating any effect that the paint has had on the adhesive.