By the Ming dynasty, seals carved in soft stones had come to replace the less durable copper stones which were subject to rust and corrosion, rendering the characters illegible.
銅印出土時，因被銅鏽侵蝕，印面模糊不清，為看出印文，必須剔去銅鏽。而剔鏽之事須由老手擔任，才不會傷了字口。到了元末，王冕首先以花乳石刻印，因石易受刃，刻者競相採用，石印大為盛行，收藏者也日眾。