. Rubber hand stamps and the manipulation of rubber; a practical treatise on the manufacture of India rubber hand stamps, small articles of India rubber, the hektograph, special inks, cements, and allied subjects . brought up to the curingtemperature 284° F. (140° C). It is possible thata second screwing up may be needed. The springpress is in such cases particularly convenient as itavoids the necessity for re-moving the press from thevulcanizing chamber, Afterhalf an hour it will be thor-oughly cured. A hole ismade through its centre fromside to side thereof, but notpenetrating the disc, andt
. Rubber hand stamps and the manipulation of rubber; a practical treatise on the manufacture of India rubber hand stamps, small articles of India rubber, the hektograph, special inks, cements, and allied subjects . brought up to the curingtemperature 284° F. (140° C). It is possible thata second screwing up may be needed. The springpress is in such cases particularly convenient as itavoids the necessity for re-moving the press from thevulcanizing chamber, Afterhalf an hour it will be thor-oughly cured. A hole ismade through its centre fromside to side thereof, but notpenetrating the disc, andthrough this hole a brassnail is thrust and bent intohook form. In the cut the correct shape for the mould andconsequently for a suction disc is shown. This canbe easily secured where a disc already made is procur-able by casting in plaster, or, with a little ingenuitythe template for the mould and the plunger to beused instead of the marble can be whittled out ofwood. The lower body of the mould in such a casecan be made of plaster of paris. To secure thealignment of the two parts of the mould, dowel pins,indicated in dotted lines, should be placed near theperiphery. The gum should be introduced in a lump. Mould for Suction Discs. AND THE MANIPULATION OF RUBBER, 89 near the centre, in order that it may sink well down-wards to the bottom of the mould before spreadinglaterally. Sometimes the tips have a recessedend. This is secured by the use of a mandrel,shown in dotted lines in the axis of the discs are sometimes made to be cemented toarrows to be discharged against smooth surfacedtargets, to which they adhere on impact by atmos-pheric pressure, giving rise to a very interestinggame. Another use of suction discs is as photographicnegative holders. They can be fastened to a woodenhandle and be attached by suction to the back ofa negative under treatment. For this purpose theyshould be at least two inches in diameter. Pencil Tips.—These are generally little cylinde
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Keywords: ., bo, bookcentury1800, bookdecade1890, bookidrubberhandstamps01sloa
