466 



THE INDIA RUBBER WORLD 



[June 1. 1913. 



the charge may be as high as one hundred and fifty pounds. 



What is known as the Hood washer is a two-roll machine set 



in a closed tank, so that the level of the water during washing 



comes above the nip of the rolls. When at work the rubber 

 sheet floats up to the surface automatically, and feeds through the 

 rolls. Floating impurities are washed 

 away, while the heavier ones sink to 

 the bottom out of the way, and are 

 removed periodically through a gate. 



Another enclosed roll machine is 

 the Dessau. It consists of a pair of 

 rolls, corrugated and studded, revolv- 

 ing in a tank. The sides of the tank 

 support a central screened box that 

 immediately encloses the rolls. This 

 gives a liquid space at the bottom and 

 sides. There is arranged also at the 

 bottom of the liquid space an agi- 

 tating device which keeps the water 

 in motion and is designed to prevent 

 any particles of foreign matter from 

 settling upon the rubber while it is 

 being washed. 



Still another enclosed washer is the 

 Kcmpter, of German origin. This, 

 like the Masticator washer, has 

 bladed rolls, the bottom of the trough 

 containing them being in the form 

 of intersecting cylinders with a 

 ledge in the middle. Water is forced 

 in from the bottom. The rubber 

 passes down between the rolls, is 

 opened up by the ledge, and then 

 up between the rolls and the sides 

 of the trough. Foreign materials 

 puss through perforations in the 

 ivouyh and over lips on eithes wall. 



In addition to the foregoing there are sundry individual ma- 

 chines and processes in use in various factories for the further 

 cleansing and treatment of crude rubber. 



For example : In the production of a certain grade of rubber 

 great difficulty was found in getting rid of the great amount 

 of woody fibre that was present. After the rubber had been 

 shredded, both rubber and wood floated on the surface of the 

 water, and if i)Ut through ordinary roll washers much fibre 

 was imbedded in the rubber. One solution of the problem was 

 a method of 

 dissolving the 

 wood fibre by 

 treating the 

 mass with a 

 strong alkaline 

 solution. After 

 many experi- 

 ments a simple 

 process for re- 

 moving most of 

 it mechanically 

 was invented. 

 It was this : to 

 float the shred- 

 ed rubber and 

 fibre into a tank 

 that could be 

 hermetic- 

 ally sealed. 



.\ir was then forced in and the pressure freed the minute 

 globules of air that clustered about each shred of fibre, and the 

 shred, water-logged, sank to the bottom out of the way. 



The above covers pretty fully rubber washing where water 

 alone is used. Where rubber is washed free from resins, for ex- 

 ample, and solvents are used, a radically different apparatus is 

 necessary. That, however, is another storv. 



AxGLE Type Two Roll W.^sher. 



The Dessau "Rock 



