It is claimed[34] that the production of "slab" rubber by standardised methods eliminates to a great degree the variability which at present characterises plantation rubber, and that a fast-curing medium is obtained. These claims will be discussed in later chapters dealing with the vulcanisation of rubber, and demand no notice in this section. [34] "Preparation and Vulcanisation of Plantation Rubber" (Eaton, Grantham, and Day), Bulletin No. 27, F.M.S. Department of Agriculture, 1918. From the producers' point of view, it may be noted that the preparation of slab rubber is a simple process, but not altogether as pleasant probably as might be desired, when undertaken in crude form. The appearance of the partially dry slabs is unattractive, but that does not signify if the quality of the vulcanised product satisfies requirements. For the average producer, the difficulty lies in having to meet the demands of the general market. Even, therefore, if one assumes that the intrinsic qualities of slab rubber are all that the claims advance, it would be necessary for the producer to be assured of definite and regular sales. At present it would probably be fair to state that practically all the "slab" rubber being prepared is produced by those who are also consumers. They are thus in the enviable position of being able to satisfy their requirements as to the mode of preparation. Until such time, therefore, as there exists a regular demand for "slab" rubber in the general market, the vast majority of estates must proceed on ordinary lines of preparation. PART VI VULCANISATION (BY DR. H. P. STEVENS) CHAPTER XXI _INTRODUCTORY DEALING WITH TREATMENT AND VULCANISATION_ In the foregoing chapters the methods of treating latex, coagulating, rolling and curing, or drying, have been described in great detail. These details will give the reader some idea of the precautions taken, and procedure necessary to produce rubber which will be acceptable to the market. The expressions "inferior rubber," "defective crepe," "poor quality sheets," etc., are frequently met with, but these expressions must not be taken to indicate any defect in the rubber for manufacturing purposes, but merely that the rubber is defective for selling purposes--that is to say, being unsightly, it will not fetch the full market price.