670 RUBBER 



The rubber is then removed from the trays and may 

 be pressed into blocks; as in the case of Fine Hard Para, 

 it contains from 10 to 20 per cent, of moisture, and the 

 inner layers are white till exposed subsequently to the 

 atmosphere. The exact depth of tray which is most 

 convenient has still to be ascertained; the shallower the 

 tray, within limits, the greater is the quantity of latex 

 which can be treated on any one day, since more trays 

 can be used in a smoke chamber. The chief drawback 

 to the process is the number of trays required; economy, 

 however, can be effected by using comparatively large 

 trays. The advantages of the process are : (a) The fact 

 that the rubber need be handled only once in a week 

 or fortnight when removed from the trays; and (b) the 

 rubber will probably be very uniform throughout, since, 

 unlike rubber made from the latex on any one day, which 

 may vary from day to day, the daily variations will be 

 corrected in a slab or sheet which is formed from latex 

 obtained daily over a period of, say, seven to fourteen 

 days. The uniformity appears to the author to be the 

 most important point in connection with the process, and 

 probably explains the greater uniformity in Fine Hard 

 Para, each ball of which is prepared from latex collected 

 over a prolonged period. 



Since these experiments were commenced by the author 

 a patent has been applied for in Malaya by another experi- 

 menter who has evidently been working on similar lines. 

 It is not possible at present to say definitely whether the 

 process will work satisfactorily on a large scale, as, in 

 the author's experiments, only about twelve trays were 

 used in the smoke cabinet employed. Experiments on a 

 larger scale will be conducted shortly and the samples 

 vulcanized and tested. 



Defects in Raw Rubber and their Remedy. 



The principal defects to which objection is taken by 

 buyers are the following: (i) Tackiness; (2) spots due 

 to fungi and bacteria; (3) oil marks; (4) holes in crepe; 

 (5) yellow patches in pale crepe; (6) over-smoking; 

 (7) dark colour in unsmoked rubber; (8) rust marks. 



