How many letters does the top answer for “duplicator consisting of a gelatin plate from which ink can be taken to make a copy” have?

The most common answer is hectograph (10 letters).

Crossword clue: duplicator consisting of a gelatin plate from which ink can be taken to make a copy

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

hectograph 10 letters wn-def

duplicator consisting of a gelatin plate from which ink can be taken to make a copy

heliotype 9 letters wn-def

duplicator consisting of a gelatin plate from which ink can be taken to make a copy