How many letters does the top answer for “to prepare by heat (the materials for making glass); to fuse partially. ure.” have?

The most common answer is frit (4 letters).

Crossword clue: to prepare by heat (the materials for making glass); to fuse partially. ure.

1 answer found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

frit 4 letters web-def

The material of which glass is made, after having been calcined or partly fused in a furnace, but before vitrification.