MATRICES
The ordinary practice followed in making mats is to use an electrotype or stereotype pattern plate made from the original form. Sometimes the original itself is used.
The first mat molded from an electrotype pattern plate will be sharp. The next one molded will be a little less sharp than the first. The third one molded will be slightly less sharp than the second one. In other words, with every succeeding mold, the electrotype or stereotype pattern plate is mashed a little by the pressure of the matrix press until it has to be discarded and a new one used.
The five-thousandth mat made by the Rapid Electrotype Company from the same pattern plate is as sharp as the first one molded. This is because an aluminotype pattern is used from which to mold. Aluminotypes will not mash under the pressure of the matrix press, as they are much harder than electrotypes.