How many letters does the top answer for “having the property of becoming permanently hard and rigid when heated or cured” have?

The most common answer is thermoset (9 letters).

Crossword clue: having the property of becoming permanently hard and rigid when heated or cured

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

thermoset 9 letters wn-def

having the property of becoming permanently hard and rigid when heated or cured

thermosetting 13 letters wn-def

having the property of becoming permanently hard and rigid when heated or cured