162 RUBBER AND 



stream of water. The washing of sheet rubber is there- 

 fore largely superficial. 



Creping machines have grooved rollers which revolve 

 at different rates. The grooves may be arranged in a 

 diamond pattern, or the roller may have plain parallel 

 grooves disposed either longitudinally or in a slight 

 spiral. The relative rates of revolution of the rollers 

 varies between 2 : 1 and 6:5. When the rubber is passed 

 between such rollers, set fairly close together, under a 

 stream of water, the rubber is stretched and torn and 

 the washing is much more complete than if the rollers 

 revolved at an equal rate. The rubber leaves the 

 machine in a long lace-like strip, which is a convenient 

 form for rapid drying. 



Macerating machines are similar to creping machines, 

 but have coarse grooves and a high differential rate of 

 speed. They are employed in the preparation of crepe 

 from bark-shavings and other sources where there is a 

 large amount of impurity to be removed. 



Drying. 



The simplest method of drying the rubber is to hang 

 up the strips of crepe or sheets in a large and airy room. 

 Light must be carefully excluded from the drying room, 

 and thorough ventilation must be provided for. In the 

 moist climates in which rubber is generally grown, 

 drying is a very long process unless artificial means are 

 employed for removing the moisture of the surrounding 



