Meaning of smoke proof | Babel Free

Definitions

A temporary print made from a thin coating of carbon deposited on the punch surface by a candle flame, used in evaluating the progress of the design of the punch.

historical

Examples

“Progress was observed from time to time by holding the end of the punch in the sooty flame of a candle or lamp and by pressing it on slightly damp paper to make a smoke proof.”

CEFR level