174 RUBBER AND 



hackneyed comparison with the conditions of an up-to- 

 date dairy may profitably be borne in mind. The 

 practice of frequent cleaning should extend to the 

 tapping tools and collecting cups. It has been recom- 

 mended that the latter should be of glass or earthenware, 

 since proper cleansing is difficult with any form of metal 

 cup. Glass or earthen cups are unfortunately very liable 

 to be stolen on small estates. 



The growth of mould fungi on the rubber sometimes 

 causes trouble in wet weather. As a rule little damage 

 is done in this way, the action being entirely superficial. 

 Moulds seldom appear in large factories where the 

 preparation is rapid and the storing and packing rooms 

 are kept dry. Smoked rubber is practically immune 

 from the attacks of moulds, owing to the antiseptic 

 properties of the smoke constituents. 



Tackiness. 



Rubber is said to become tacky when the surface 

 turns soft and sticky. In some cases the softening may 

 proceed so far that whole sections of rubber fall to pieces 

 and dissolve into a liquid form. Tacky rubber is useless 

 for the ordinary purposes of manufacture, and can only 

 be sold at a low price as a subsidiary product. The 

 condition is rightly dreaded as the worst defect which 

 can possibly arise. 



One certain cause of tackiness is exposure to sun- 

 light, and it is to guard against tackiness that drying 



