Other defects may arise which can be traced to faulty treatment of the marked coagulum prior to hanging in the smoke-house and subsequent to rolling. These will be enlarged upon in a [subsequent section] of the book, and at present it will suffice to indicate the procedure which experience directs as likely to give the best results.
When the lengths of coagulum leave the marking machine they are usually laid in piles containing two dozen or more strips. The piles are then cut into the required lengths, the exact length generally being determined by the available perpendicular distance between the supports in the smoke-house. It is necessary to remark that the piles of sheets should not be allowed to accumulate, but should be dealt with in subsequent treatment progressively. If for some reason this is not possible, then all piles of sheets should be turned on edge so as to assist the draining away of the serum or “mother-liquor,” which continues to ooze from the rubber for some time after the squeezing in the machines.
Where hot water is available the freshly cut sheets should be passed into it as soon as possible, and given a thoroughly good swilling. The caution must be given that the hot water should be changed very frequently and, if possible, after every batch, say, of a hundred sheets.
The sheets should then be carried immediately to racks on which they are hung to drip. Generally these racks are situated under cover, but there is no reason why they should not be placed in the open air without cover or shade. From continued experience of this practice over a period of years it is found advantageous and to be preferred to the usual method of allowing sheets to drip under cover.
While the sheets are fresh and loaded with internal moisture, the effect of sun-heat upon the surface, when exposed for, say, two hours, is nil; and the safety of the process can be guaranteed, provided the stated limit is not exceeded to an appreciable extent.
The Old Method of “Dripping” Freshly Rolled Sheets
within the Factory.
After dripping for an hour or so, the sheets should be placed in the smoke-house. If it is a bright sunny day, no extra precautions need be taken; but on cool, dull days it would be advisable to light the fires earlier than usual, consistent with the work required to be done in the house—e.g., in the removal of dry rubber. There would appear to be no reason why the dry sheets should not be first removed, so that on dull or wet days smoking can be commenced as soon as the wet rubber has been hung.
On a few estates where the smoke-houses are worked continuously, except for a few hours in the morning, a portion of the building is separated by a partition for the reception of the wet rubber. The sheets are taken directly from the marking rolls and placed in the chamber, beneath which a fire is started. The sheets thus drip in a warm and smoke-laden atmosphere until next morning, when they are weighed and removed to the smoke-house proper. It is claimed that freedom from “rust” is thus obtained.