What is Electrotyping?
It is the process of copying medals, type, wood-cuts, engraved copper and steel plates, etc., by means of electrical deposition. It is chiefly used for making, from the ordinary movable types, plates of fixed metallic types, for printing books.
Describe the process.
The article to be copied is first covered with black-lead, and then a mould is made of it in wax or gutta-percha. This mould is placed in a solution of sulphate of copper, and attached to the negative pole of the battery, while a plate of copper is hung from the positive pole. The electric current decomposes the copper, which is deposited in a thin film upon the mould. This film is removed and stiffened by being backed with metal.
What is the difference between Electrotyping and Stereotyping?
In stereotyping, a plaster of Paris mould is taken from the types, and upon this mould melted type-metal is poured, which, when hardened, makes a solid plate.
Is there any other method of stereotyping?
Yes; that known as the paper process. A uniform sheet of soft matter is formed by pasting together sheets of thin, tough tissue paper. The types are oiled, and the soft, moist sheet is placed on them and beaten down with a stiff brush until it receives an impression of the type-form. Both are then run through a press, and on being taken out the paper is found to form a perfect mould. Into this mould the type-metal is poured and the plate formed.
Can you tell me some magnetic effects of the current?