List of therms» Talc

Talc, sometimes called French chalk or talcum powder, is a dehydrated magnesium silicate. It is used, like rosin, as an acid resist on stone and metal plates, although it is less resistant than rosin. When used with rosin, talc lessens the surface tension of the printing element in the presence of watery solutions of gum arabic or acid. Talc can sometimes be used alone as an etch resist on metal plates, because the acid etches employed on metal are relatively weak. It is also employed throughout the shop as an cleaning agent, to dust the hands, press box, paper table, ink slab, or color roller after use.