July 1, 1921 



THE INDIA RUBBER WORLD 



717 



The Manufacture of Dipped Goods 



By John 



THE manufacture of "dipped" goods is commonly conducted as 

 a department in a factory making druggists' rubber sundries, 

 although there are numerous small manufacturers whose en- 

 tire output is made by the dipping process. 



The important rubber goods made by the dipped process are 

 chiefly housekeepers', surgeons', and undertakers' rubber gloves, 

 toy balloons and nursing nipples. These goods contain from 70 

 to 100 per cent pure rubber by weight and for that reason have 

 great elasticity and toughness, characteristics on which their value 

 chiefly depends. 



Dipped goods are cold-vulcanized by either the "acid" or "vapor' 

 cure. For that reason they admit of brighter coloring than goods 

 vulcanized by "hot" vulcanization. If made with expert care 

 dipped goods will render satisfactory service for a reasonable time. 



FACTORY PLAN 



The manufacture of dipped goods is often conducted in premises 

 and with plant arrangements not best-suited to the work. In addi- 



Hadfield 



red oxide or other mineral pigment is used for coloring. Com- 

 pounding for dipped goods presents simple conditions and few dif- 

 ficulties. 



CEMENT 



The solution of pure or compounded rubber is known as cement. 

 The solvent employed is 56 to 58-degree naphtha. This grade of 

 naphtha should completely distil under ISO degrees F. and is better 

 suited for use in making cement for dipped goods manufacture 

 than the lighter grades of naphtha or gasoline because it does not 

 volatilize so readily from the dipping tanks, and consequently does 

 not induce bubbles in the goods nor form a crusty gas-fillcd layer 

 of rubber on the surface of the stock in the dipping tank. 



Various styles of machines may be employed for dissolving 

 broken down or compounded rubber to suitable consistency for 

 use in the dipping. One of the best is the enclosed type, one style 

 of which is shown in Fig. 2. In such a tightly-closed, revolving 

 drum-like apparatus, cement may be made of very uniform con- 

 sistency because the solution chamber is tightly sealed against 



Dipping 

 ffadt/ne 



Dipping 



Work Bench 



Curing 



Ovens 



I ] Stripping 

 \/ i Table 1-^ 



/ U 



Soapstone 

 Drawer 



Soapsfom 

 Drawer 



Mill and Cement Room 



Dipping Room 



Finishing Room Curing Room x i ^r ^ n , • r, 



-' Take Off and Packing Room 



cfilotfed Bench for Drying 



Nipple and finger CulMachme 



Work Bench 



Acid Tank 



Acid Tank' 



Tesfingand 



lettering 



Balloons 



<-Tumbler 



Fig. 1. Plan of a Model Dipped Goons Factory 



tion to conveniently-arranged space and the proper machinery, 

 consideration may profitably be given to providing adequate day- 

 light, eflfective ventilation, and a scientific air-conditioning systein 

 for thoroughly drying the goods in process. 



Various floor plans are possible and some may prefer a two- 

 story arrangement to the single-story plan shown in Fig. 1. 

 Provision is made in this plan for a rubber milling and cement- 

 making room ; dipping room ; finishing room ; curing room ; strip- 

 ping, testing and packing rooms. 



MATERIALS AND PROCESSES 



RUBBER 



In the manufacture of dipped goods only clean grades of fine and 

 plantation Para rubber are available. Of these the choice favors 

 Beni Bolivian as yielding goods of superior tensile strength. 

 First latex plantation is essentially as good in this respect and 

 superior for light-colored and transparent goods. 



It is essential that the rubber employed be clean and well dried. 

 Breaking down the crude gum is usually limited to IS to 20 min- 

 utes on a warm mill, at which point it is ready for solution if 

 destined for making pure-guin goods. If for balloons or com- 

 pounded stock the selected proportions of rubber, color and litho- 

 pone are milled to a uniform mixture by grinding on a hot mill 

 for about 25 minutes. 



'.■■'■ COLORS 



Tha- colors used are oil-soluble aniline pigments such as red, 

 blue, ypllow, black and other, colors. White is obtained by means 

 of lithQpojie. This material is also used in connection with the 

 anilines to dilute and improve the resulting color of clear tints. 



In compounded goods, such as gloves for household use, Indian- 



loss of solvent by evaporation. There is another and more impor- 

 tant advantage to be noted, namely, minimizing the fire risk from 

 static electricity. 



The proportion of solvent in dipping cement for balloons and 

 pure-gum goods is two gallons to each pound of rubber. In the 



EiMco Rubber Cement Mixer 



case of compounded gloves the proportion is 35 gallons to SO 

 pounds of rubber composition. 



cement for transparent nipples 



Transparent nipples are made from the lightest first late-x planta- 



tiop rubber available. Frequently that fromi Ceylon is specified. ■ 



Care must be t^l<?n that the gum is not ov?j-,milled in breaking 



down, otherwise it will become darkened. The milled gum is 



