SEPTEMBER, 1950
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RUBBER STAMPS OF AROMATIC RING SYSTEMS ROBERT IRVING WALTER Universib of Colorado. Boulder, Colorado
W R m m N notes and papers on organic chemistry can he prepared more easily if rubber stamps are available for the aromatic ring systems discussed. These are prohibitively expensive if made to order and are relatively difficult to carve from wbher stoppers as suggested by Fieser.' Quite complicated ring system can easily be cut from one-ply laminated gasket rubher, which consists of two layers of rubber approximately 1 mm. thick vulcanized over a center layer of cloth. The latter prevents distortion during cutting and permits easy removal of material inside the ring outline. The pattern can be transferred to the rubber by marking the intersections of lines with pinholes, or with water-soluble white ink. The rings are cut using tn-o safety razor blades held in a jig consisting of three layers of sheet. metal between which the blades are bolted. The center layer has a thickness equal to the width of the lines in the completed stamp. The edges of the blades should project far enough to cut through the top layer of rubber only, leaving the cloth center unt.ouched. For small rings, it may be convenient to break away part of the edge. Cuts can be made through the intersections of the lines; they will not show in the stamped impression. After the ring pattern is cut, the rubber around the lines can be peeled away from the cloth center layer, leaving only the ring pattern. This process can be started by bending the rubber around a finger and working under the slightly projecting corners with a knife. The finished patt,erns are mounted with rubber cement on rubber stoppers, and the excess rubber finally cut away close to the edge of the stamp to facilitate liming it up in use. S t a m ~ sUD to ten centimeters
FIESEE, L. F., ''Experiments in Organic Chemistry," 2nd ed., D. C. Heath and Co., Boston, 1941, p. 297.
square containing both rings and block letters have been made by this method. The illustration shows a completed stamp of the porphyrin ring system and the impression made from it.
Rubber stamp .nd print
