374 THE INDIA RUBBER WORLD [April 1. 1915. 



Recommendations for the Treatment of Latex and Curing 



of Rubber. 



THE Rubber Growers' Association, ol I ondon, lias pre- will undoubtedly prove a great convenience to the workmen 



pared a number of recommendations covering all th« in the factories on the plantation, as the instructions which 



important features oi securing tin- latex and curing the they should follow will always be immediately under their 



rubber These recommendations have been printed in the eye. ^s a matter of fact, an intelligent workman in a short 



i i .if a hanger _' feet long by 1.1 inches wide and given time i- likely to have these rules for preparing rubber, given, 



permanency bj being hacked with linen and finished top and as the) are. in condensed form, indelibly impressed upon his 



bottom with brass edging, tin intention being, evidently, that memory. 



the banner -hall hang on the wall for eas\ reference. ["his The recommendations are repi oduced ill full below: 



bill-: RUBBER GROWERS' VSSOCIATION (incorporated). 



IATIi X- FOR Till: TREATMENT U LaTEX VXD I URING C] RUBBER. COMPILED BY Till. UNIF0RM1T¥ COMMITTEE FROM 



Information Supplied p.\ thi Scientific Staff. 

 GENERAL. 

 1. — Cl i -. Bi i ki rs vnd OTHER i ik.nsii - should be selected with a view to ease in cleaning and should be kept absolutely clean. 

 \. -. !. made "i copper, or am alloj of cupper, and kerosene tins or receptacles with similar angles should be avoided. 



2. — Water in Cups.— In most cases addition of water i- quite unnecessary. A little clean water may he used in very dry 

 weather, when the latex tends I-' coagulate ver) quickly. In some instances a little formalin or sodium sulphite {not bisulphite) 

 may be added, but application should be first made to the laboratory tor advice before using these reagents. 



3. — Water on the Transverse Cuts i- not advisable. < >ften the latex coagulates as a result of employing water on fresh cuts. 

 4. — Bark SHAVINGS and other impurities should not be allowed in the cups or buckets. 



5. — Collection of Latex. — Latex should not be allowed to stand in the field. The earliest opportunity for collection should 

 lie taken. It is recommended that in collecting, the following grade- be recognized and kept separate: 



(c) I ban uncoagulated latex: I b > Lump, coagulated in the cups: (c) Rinsings from the cups 



6. — Transpori 0] Latex.— Ever) possible means of facilitating quick transport should be taken. When distance of transport 

 :- gre • out station coagulating houses should be erected. 



IX THE FACTORY. 



RECEPTION OF LATEX. 



7. — Pkeliminak\ Treatment.— The latex should be received if possible on a verandah, so that there is no necessity for coolies 

 iter the building, thus avoiding the presence of dirt ill the factory. 



8. — Supervision. — The reception of latex should be under direct European supervision. Causes of defects in preparation of 

 the finished rubber are thus often detected. 



9. — Cleanliness in utensils and method- i- absolutely necessary; any neglect in tin- respect is sure to detract from the quality 

 of the rubber. 



10. — Straining m Latex should be thorough, care being taken to see that the mesh is in good order. 



11. — Bulking of Latex is strongh recommended. Tin- mixing of all latex undoubtedly tends to produce a rubber of greater 

 uniformity. 



12. — Sodium Bisulphite. — For crepe manufacture dissolvt '_ lb. of the powder in 1 gallon of water. This will be sufficient for 

 Jo gallon- of in, diluted latex. The solution should be well stirred in after bulking and before the addition of acid. Larger 

 quantities of -odium bisulphite are quite niin eessary. Sodium bisulphite should not be used in making sheet rubber. 

 Note. — Latex containing more than 35 per cent, of rubber maj be taken as "undiluted latex." 



COAGULATION. 



13. — Coagulant. — Acetic acid i- recommended as the best coagulant at present. 

 14. — Strength oi Solution.— Stock solutions should be made up a- follows 



For Making Crepe. — Take one pan of concentrated acetic acid, of 98 to 100 tier cent, strength, and dilute it with 

 20 parts of pure water. 

 (b) I'ur Making Sheet. — lake one pan of concentrated acid, of 98 to 100 per cent, strength, and dilute it with 200 parts 

 of pure water. 

 If in making these stock solutions a more diluted acid be e nployed such a- an acid of NO per cent, strength, a proportionately 

 greatei amount of acid must be taken: thus with an NO per cent. acid. 1 ' j part- must be taken instead of one part. 

 In effecting coagulation the maximum amount- of these stock solutions, which need never be exceeded, are: 

 I-/: For Crepe. — 1 part of stock solution to 50 parts of undiluted latex. 

 I SHE] i.— 1 part of stock solution to 5 part.- of undiluted latex. 



It will frequently be found tint less than these amount- i- enough to produce complete coagulation, and the minimum 

 nut which i- effective should be ascertained b\ trial 



If the latex has been diluted, a proportionate reduction in tin amount of the coagulant may be made: thus if 50 gallon- of 

 pure latex have been diluted up to 100 gallons b\ adding water, then only one part of stock solution I ,i I need be used for 100 

 part- of such diluted latex. 



15. — Mixing of acid and latex should be thorough Thi- is best effected by mean- of broad w len paddle-. Sticks must 



1 1 for this purpose When making -beet the scum should be removed and added to the lumps: 



For the preparation of crepe rubber or sheet rubber in coagulating tanks any quantit) of latex may be coagulated 



ii bulk; 

 lor sheet rubber, when ordinan dishes an' used, not more than 5H gallons of latex should be treated with acid in 

 one batch, as the latex sometimes Coa before all can In poured out into the dishes. It i- sometimes 



pedient to add water to the latex or to use a diluted solution of formalin to prevent rapid coagulation. In such 

 ■'•laired {rain the labora 



PREPARATION 01 RUBBER. 



16.— inc.— The extent to which rubber is worked on the machine- should be the minimum found necessary. 



17.— The ; of thi. Rubber determines the rate of drying Pale crepe should be rolled out thin for drying, espe- 



cially thin for artificial drying, and tin- can subsequently be worked int.. blanket crepe if desired. Sheet rubber when dry should 

 n in thickness. 

 18- S i r< Sheets shi ttld always be as uniform in thickness a- possible, and the period of -moke curing should also 



be uniform. SI exceeding : ^ in thickness should usually drv in to 10 days. 



\oii — The lust temperature for smoking is 120 deg to 130 deg. 1'". 



