CHAPTER XIV.
GLUE OR COMPOSITION STAMPS.
Stamps made from a mixture of glue, glycerine, and molasses or from similar mixtures are an excellent substitute for india rubber stamps. Properly made they possess all the flexibility that characterizes the rubber ones, while for fatty inks such as that used by printers and lithographers, which inks tend to destroy rubber stamps, they are much better. They are adopted by the United States government for making dating stamps for use in the Post Office Department; by publishers of directories for printing advertisements on the edges of their publications, and in many other cases. Our description shall follow as closely as possible the process and methods used in the United States Post Office. They are there termed “composition blotters.”
The composition of which they are made is printer’s roller material. Nine and one-half pounds of fine quality glue are soaked in just enough soft water to cover it until it is thoroughly softened. It is then melted. In the Government Department a steam kettle is provided for the purpose. An ordinary glue pot will answer for smaller quantities. When melted four and one-half pounds of best molasses and seven pounds of glycerine are added, and the whole is thoroughly mixed. The formula varies a little according to the prevailing temperature, less molasses being added when the weather is warm, and vice versa. Experience is here the best teacher. When well mixed it is poured out into tin pails whose inner walls or sides and bottom have been rubbed over with oil. It solidifies in cooling and becomes a clear brown jelly quite free from any stickiness or superficial moistness.
Model for Composition Stamp Mould.
In use it is turned out of the pails to which, owing to the oiling, it does not adhere. It is cut off as wanted, melted by heat and cast in oiled moulds.
The latter are made of type metal to which one-third its weight of lead has been added. As model for the mould or matrix a brass model of the stamp is employed. This represents a sort of oval based cut-off or truncated cone, about an inch high and a little over an inch long on its base. A flange extends outward from its base and a tube is provided to fit this flange. Its smaller end corresponds to the face of the stamp, and on it are engraved in full relief any permanent characters, circles or border lines, etc. Through its centre one or more apertures are made. Into these, changeable steel, iron or brass type may be introduced and set fast with plaster of paris.
Composition Stamp Mould.