May 1, 1917.] 



THE INDIA RUBBER WORLD 



445 



Making Seamless and Transparent Rubber Goods. 



THE manufacture of seamless and transparent rubber goods 

 in the United States has not experienced the unusual 

 growth that has characterized other branches of the rubber 

 industry. In the past this has been almost wholly due to the 

 competition of German manufacturers, who were able to under- 

 sell the American producer, and thereby control the market. 

 Now that this depressing competition has been removed, the 



'tfaioi;"! If 



Fig. 1. M.-^CHiNEs for Making Dipped Goods in Quantities 



manufacture of dipped goods will, doubtless, be developed to a 

 much greater e.xtent than ever before, and when American in- 

 genuity is applied to this branch of the rubber business there will 

 be small reason to fear competition from abroad. The demand 

 for transparent and seamless rubber articles made by the dipping 

 process has been greatly augmented 

 during the past few years, and the 

 production is not equal to the de- 

 mand. 



In this country we are accustomed 

 to view the art of dipping as an un- 

 avoidable hand process and, there- 

 fore, there has been little advance- 

 ment made in specialized dipping 

 machines. That Germany has taken 

 precedence in dipped goods manu- 

 facture is a well-known fact, due, 

 without question, to" the labor-saving 

 machinery of special design used in 

 making goods of this type. In de- 

 sign and construction these machines 

 are built for both large and small 

 production, and with every pos- 

 sible operation being automatic- 

 ally controlled in order to conserve 

 labor and reduce the cost of manu- 

 facture. 



GERMAN METHODS. 



In the manufacture of nipples, according to the German 

 practice. Upper Congo, Mozambique, Para and Ceylon rubbers 

 are used. In order to cheapen the article, rubber substitute is 

 often employed, but the resultant product is dull in finish and 

 requires varnishing or enameling. Red nipples are made from 

 Ceylon rubber, colored with sulphurct of antimony, and for black 

 nipples Para rubber is generally used without coloring matter 

 of any sort. Ceylon rubber is unsuited to this type of nipple, as 

 it produces a gray-blue color in the goods. 



Benzene of high volatility is recommended, as the lower grades 



have a tendency to produce blisters. The solution is made in the 

 ordinary vertical type of power-driven churn, although recently 

 the Universal solution churn has come into more general use. 



In the preparation of crude rubber for the manufacture of 

 transparent goods the procedure is radically different from that 

 of ordinary seamless goods. Para, Ceylon and Ceara mixed with 

 African rubber of good qirality may be used. Pale Ceylons are 

 very satisfactory and the Brazilian 

 sorts . when used alone, produce 

 slightly opaque goods, but quite 

 nervy, while with African rubber 

 they are both softer and clearer. In- 

 ferior rubbers are not used in the 

 making of transparent rubber goods. 

 As heat makes the rubber opaque, 

 the washing process is precluded and 

 the rubber is cut in small pieces and 

 dissolved in benzene in a solution 

 mixer. The heavy impurities may be 

 strained out, but the fine particles are 

 removed by a settling process ; the 

 time required to produce a perfectly 

 pure solution depending on the qual- 

 ity of the gum and the required thick- 

 ness of the solution. The dipping 

 forms may be of wood, porcelain or 

 glass and the frames to which they are attached are all of stand- 

 ard size to fit the dipping machine carriers. 



SCHIRM'S DIPPING MACHINES. 

 .Seamless goods, such as toy balloons, nipples and gloves, trans- 

 parent, nipples, finger cots and tubes are all made on the machines 



m 7 





Fig 



Machines for Making Dipped Goods with Movable Solution Car. 



here described; however, the preparation of the solution, and the 

 drying and final vulcanization is quite different in the production 

 of transparent articles. The machines for dipping and drying 

 nipples and similar articles up to 180 millimeters [7.086 

 inches] in length are illustrated in Fig. 1 and consist of a battery 

 of 5 machines. The detailed description that follows applies to 

 each machine, as they are all alike in construction and operation. 

 Moreover, the process of dipping and drying is progressively 

 carried on, the machines being semi-automatic and under the con- 

 trol of one operator. 



The upper cylindrical casing encloses a horizontal shaft on 



