| abstract |
An undercoating is deposited on a glass workpiece and an overcoating is applied upon the undercoating. Then a plurality of related marks is recessed through the overcoating, thereby producing the novel workpiece. Each of the undercoating and overcoating is comprised of pigment particles and an alkali silicate binder. The alkali silicate binder of at least one coating, and preferably both the undercoating and the overcoating, consists essentially of a mixture of sodium silicate, potassium silicate and lithium silicate. The coatings are made from aqueous suspensions of pigment particles, dissolved sodium silicate, dissolved potassium silicate and lithium-stabilized silica sol. |