How to visually distinguish drywall or plasterboard from cement asbestos millboard Above we illustrate a fragment of cement asbestos millboard that is about 1/8 thick and his hard - cementious, and at above right we take a look at the edges of two layers of drywall or plasterboard in an older home - showing that that material, principally made of gypsum, is comparatively soft, paper-faced, and ea