I have been working on this plate lately. It is a copy of Gian Lorenzo Bernini’s Andrew & Saint Thomas 1627 paintings (National Gallery, London).
Stage I: tracing on hard ground + 45 minutes bathing:
Stage II: soft ground marked with latex gloves + liquid ground around the lines + 30 minutes bathing
Stage III – liquid ground + open bitting only on the top edges around the faces (45 minutes)
Detail Stage III