fine-tooth comb

because the adjective 'fine' qualifies the noun 'tooth', like 'a 35-hour week' or 'a s**t-covered pig'. Of course grammatically speaking, 'a fine tooth-comb' is correct, but differs semantically. It suggests either a very thin or a very posh comb (with teeth).

Fine-toothed is ok as well, as it is the adjectival past participle of 'fine-tooth' (like 'the shop is opened at 9.00' vs 'the shop is open at 9.00').

hope that clears things up.

Posted By: Dave in France, Nov 22, 12:28:27