vitrified

(verb) change into glass or a glass-like substance by applying heat. Synonyms: vitrify.

(verb) undergo vitrification; become glassy or glass-like. Synonyms: vitrify.

(adj) (of ceramics) having the surface made shiny and nonporous by fusing a vitreous solution to it. Synonyms: glassy, vitreous. Examples: "Glazed pottery." "Glassy porcelain." "Hard vitreous china used for plumbing fixtures."