Stereotyping
The art of obtaining metal plates about 3/16 inch in thickness from pages of type previously set up in the ordinary manner. The art was invented by William Ged of Edinburgh, 1725. The forms of type are first laid on a smooth table, face upwards, oiled, and after the frame or flask which regulates the depth of plaster has been placed around, the surface is covered and swept off even. This cast is then dried, and afterwards turned face down on an iron floater, and the whole is placed within the dipping-pan, the lid of which fits the pan except at each corner, where provision is made for the entrance of the fluid metal. A clamp stretching across the pan serves to bind all together, and furnishes means for suspending and lowering into the bath, where it is immersed well down, to create a pressure, which causes the metal to spread and fill every cavity precisely, the thickness being regulated by an adjustment between the plaster-cast and floating-plate. The metal used for this purpose is various; some use type metal; others, lead 100, antimony 15; and, again, lead 4, antimony 1, tin 1; but generally the alloys contain from 4 to 8 lead to 1 of antimony, according to hardness required. It must be understood that antimony acts to neutralize the contraction of lead, and causes the alloy to give a correct impression of the mould. See TYPE-METAL.