Abstract: A glare-reducing coating to aid visual inspection of bright surfaces such as on printed circuit boards and assemblies, which, when applied from a liquid solution, selectively diffuses light on metal surfaces while remaining transparent over plastic substrates. The optical, tack-free coating is readily cleaned from surfaces by conventional soldering flux solvents and aqueous cleaning solutions. The tack-free, solderable coating greatly aids the visual inspection of the coated circuit board by eliminating spectral glare, and becomes transparent when heated to soldering temperature to indicate the area of rework. The coating comprises a combination of a thermoplastic rosin, suitable as a soldering flux, and DMSO in a suitable solvent, preferably consisting of or including chlorinated solvents such as methylene dichloride, thus to insure a non-flammable coating which is readily applied by dipping, brushing, or spraying.