thin copper plate

The crushed ore leaving the mill was allowed to flow over an inclined copper plate covered with a thin layer of mercury.

离开磨机的破碎矿石溢流到一个有薄汞层的倾斜铜盘中。

Aquatint: it is an etching process on copper or steel by means of nitric acid. in this technique a thin layer of resin dust is sprinkled on the plate and heated to make it adhere.

水彩色调：用硝酸在钢片或铜片上作腐蚀的蚀刻法。这个技巧是在版面上洒上一层薄薄的树脂粉，加热把它粘附于版面。

A copper plate. covered with a thin coating of wax, on which lines are cut through the wax exposing the bright surface of the copper for further processing.

在一块涂上薄蜡的铜片，用手工在蜡面进行雕刻，把线条等刻穿蜡层，露出铜墙铁壁的光泽表面作进一步的加工处理。