electrotype

[Eng. electro, and Gr. typos =a figure, an image, typto =to strike.] 1. The act or proce of producing copies of medals, woodcuts, ., by means of the electric deposition of copper upon a mold taken from the original. 2. A copy, usually in copper, of a form of type. A page of the type is covered with wax, which is driven into the interstices by powerful pre ure. The face of the wax-mold is covered with plumbago to give it a conducting surface to which the metal will adhere. The positive pole of a battery is attached to the mold, and the negative to a copper plate, and both are plunged into a bath of sulphate of copper in solution. The copper is deposited on the face of the mold in a thin film, which increases in thickne as the proce continues. The shell having attained the thickne of a stout sheet of paper, the mold is removed from the bath, the shell detached and strengthened by a backing of type-metal. This proce is called backing-up. As type-metal will not readily adhere to copper, the back of the shell is coated with tin, and the shell is