This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1907 edition. Excerpt: ...moulding of celluloid articles is carried out as follows: --The cellulose material is converted into pyroxyline by steeping in a mixture of sulphuric and nitric acids, and is then removed from the acid, washed in water, and allowed to dry for 12 to 24 hours. Then this mass, while still warm, is put into a ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1907 edition. Excerpt: ...moulding of celluloid articles is carried out as follows: --The cellulose material is converted into pyroxyline by steeping in a mixture of sulphuric and nitric acids, and is then removed from the acid, washed in water, and allowed to dry for 12 to 24 hours. Then this mass, while still warm, is put into a solvent, such as methyl-alcohol, ethyl-alcohol, sulphuric ether, to which gums, balsams, resins, colouring matters, etc., have been added, the solvent being mixed in the proportion of J gallon to 2J lb. of pyroxyline, but the quantity varies according to circumstances. The proportions of the other ingredients also vary according to the colour, tenacity and degree of hardness of the mass. The mass is then heated in a suitable vessel at 150 to 220 F., whereby it becomes plastic. It is ground, thoroughly mixed, and dried at a temperature not exceeding 150 F., when it is put, while still plastic, into the desired mould. The working of cellulose is carried out in a similar manner to the treatment of all hornlike substances; the same instruments may be used for turning, boring, and planing it. By heating it to 165 F. it becomes sufficiently plastic to assume any desired form. It is necessary to heat the mould, which should be of brass, before pressing the celluloid article; which should be cooled off in the mould by means of cold water. The length of time for the celluloid to remain in the mould depends on the temperature; if it be below 165 F., only a few minutes in the mould are sufficient. For polishing celluloid, very fine pumice stone and powdered emery, mixed together in equal quantities and kneaded into a dough with hot soap (free from resin), is used. This compound is dried, and then spread upon the polishing instrument. When the articles are..
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