CHAPTER X

PREPARATION OF CREPE RUBBER

First consideration, fine pale crepe--Standardised dilution of latex--Coagulation and coagulant--Quantities of coagulant-- Colour of rubber--Sodium bisulphite (use of)--Evaluation and deterioration of the bisulphite and sulphite of sodium--To distinguish between these two chemicals--Care of sodium bisulphite--Mixing solution with latex--Former methods of making pale rubber--Working the coagulum--Lower grades of crepe--Naturally coagulated lump--Skimmings and washings-- Tree-scrap--Bark-shavings--Earth-scrap--Fibrous matter in low- grade rubbers--Scrap-washers--Compound crepes--Increased care with lower grades--Block rubber from crepe--Smoked crepe _versus_ sheet clippings 110