Cobalt chloride/resin hygroscopic coating - for colour indication of atmospheric moisture changes

摘要

Cobalt chloride based moisture sensitive coating comprises (pref.) 4 wt. % boric acid, 4 wt. % of an aqs. 0.25 wt. % rhodamine soln. 1.2 wt. % of a melamine-sulphonamide -HCHO fluorescent pigment. 30 wt. % maize starch, 14 wt. % aqs. 12% PVA soln. and 16 wt. % of a 50% aqs. soln. of a vinyl acetate-maleate copolymer. Coating adheres well to smooth surfaces, changes colour even with small moisture changes, and can be sprayed on.