SMOKING OF RUBBER.--The assumption may have been noted above that the sheet is to be smoked. As far as our knowledge extends, none but small native estates now prepare sheet rubber of any other type, with the exception of certain patent processes. Air-dried sheets are generally made on small-holdings, and are bought in the market chiefly for the purpose of macerating and making into blanket crepe. We have no intention, therefore, of discussing the possibilities or qualities of air-dried sheets, as the output of sheet-rubber from our estates is always in smoked form. The drying (or, properly, smoking) stage will be discussed in Chapter XI. CHAPTER X _PREPARATION OF CREPE RUBBER_ NO. 1, OR FINE PALE CREPE.--Considering first the preparation of the highest grade, fine pale crepe, it must be stated that the difficulties attached to the process are generally not sufficiently appreciated. In this pale rubber minor blemishes are so plainly apparent that their importance is highly exaggerated, and what would worthily escape notice in smoked rubber assumes disproportionate prominence in pale crepes. The very fact that such a delicate material as colourless coagulum has to be manipulated in coarse iron rollers, with the attendant oil and grease worries, should be sufficient to deter one from criticising too harshly the occasional lapses of an estate struggling to give of its best to the market. At the same time there can be no doubt that if precautions are taken to attend to all likely sources of contamination, defects in pale crepe may be avoided to a wonderful extent; and on some estates the observance of elementary rules enables the preparation of the finest pale crepe to be made almost mechanically. STANDARDISATION OF LATEX.--The question of the standardisation of latex has been dealt with in a general way in Chapter VII., and the reader is now familiar with the trend of the argument in its favour. It will be recognised that the necessity for standardisation exists to the same degree in the correct preparation of pale crepe as in the case of smoked sheet. Unless the dry rubber content is invariable, and the quantities of chemicals fixed, the colour of the crepe may vary appreciably. It may be pointed out that it is not _essential_ to adopt the same standard of dilution as for sheet preparation. Given that latices from all fields or divisions are fairly uniform, and of high rubber content, the standard may be taken at a figure equivalent, for example, to 2 lbs., or 2-1/2 lbs., or even 3 lbs. per gallon. It is wise, nevertheless, to take a lower standard for several reasons. For instance: (_a_) The average dry rubber content varies with climatic conditions, position of the cut on the tree, general health of the tree, etc. On a rainy day the dry rubber content may be lowered too greatly by adventitious circumstances.