Two-colored patterns made by scraping away the upper layer (paint) and uncovering the substratum (gold, sometimes silver or tin leaf). In painting, the term is known since Vasari.

Source: Skaug, Erling. Punch Marks from Giotto to Fra Agelico: Attribution, Chronology, and Workshop Relationships in Tuscan Panel Painting: with Particular Consideration to Florence, c.1330-1430 (Oslo: IIC, Nordic Group, the Norwegian section, 1994), pp. 13-14.