Abstract: This invention relates to the production of essentially transparent glass-ceramic sheet useful as surfaces for smoothtop cooking stoves which will display a warm brown coloration sufficiently dark to conceal the heating element when not in use, but permitting visible observation thereof when in operation. The products consist essentially, on an analyzed basis, of 2.5-4.5% Li.sub.2 O, 1-2% MgO, 1-2% ZnO, 19.5-21% Al.sub.2 O.sub.3, 66.5-68% SiO.sub.2, 4-5% TiO.sub.2, and 0.02-0.2% V.sub.2 O.sub.5.

Abstract: This invention relates to the production of a composite article consisting of an opal glass body exhibiting a dense, milky-white appearance coated with an adherent enamel demonstrating high gloss and exceptional chemical durability. More specifically, the opal glasses of the present invention have compositions within the Na.sub.2 O-Al.sub.2 O.sub.3 -SiO.sub.2 -F system and demonstrate a softening point in excess of 760.degree. C., a strain point in excess of 490.degree. C., and a coefficient of thermal expansion (0.degree.-300.degree. C.) of about 66-75 .times. 10.sup..sup.-7 /.degree. C. The enamels of the instant invention have flux compositions within the Li.sub.2 O-B.sub.2 O.sub.3 -TiO.sub.2 -ZrO.sub.2 -PbO-SiO.sub.2 system, will fire to a high gloss in less than about 10 minutes at temperatures below about 720.degree. C., will exhibit coefficients of thermal expansion (25.degree.-300.degree. C.