The Preparation of Plantation RubberMorgan, Sidney
Science
The Preparation of Plantation Rubber
Morgan, Sidney
Rubber
Some estates prefer to handle the coagulum while rather softer, as it is
claimed:
(_a_) That the coagulum is easier to work, and sheets of improved
appearance can be made.
(_b_) That there is greater freedom from "bubbles."
(_c_) That the incidence of "rust" is lessened.
These claims are substantiated in practice; but in the case of the
third, it only holds provided that the rubber can be finished and
placed in the smoke-house almost as soon as the last sheet has been
machined.
In such cases all latex must reach the store comparatively early in the
day--_e.g._, before noon. Three hours is allowed for coagulation, and the
working of the rubber is then commenced. As a general rule this means that
the operations of rolling and marking must be completed, a short interval
given for dripping, weighing must be done, and the rubber placed in the
smoke-house before night falls (as a rule about 6.30 p.m.).
Unless factories dealing with a large crop are well equipped with
artificial light, such a course is not open to them; in any case it remains
true that night work should be avoided if possible. If, however, it can be
arranged without increasing the cost of production, there would appear to
be no objection to the early working of the coagulum as described above.
HAND-ROLLING.--As already indicated, some few estates do not give the
strips of coagulum any preliminary hand-rolling, as the rubber is
considered to be sufficiently firm to be handled into the first machine.
On most estates hand-rolling is found necessary, owing to the tendency of
the long strips to stretch unduly, giving badly shaped sheets. This
hand-rolling should be done carefully, and is best effected on a specially
constructed table. This consists essentially of an inch-thick hard-wood
plank about 2 inches wider, and 4 or 5 feet longer, than the strip of
coagulum. Along the edges of the plank, and at right angles to its upper
flat surface, may be fastened strips of wood about 1/2 inch square in
section, thus forming a shallow tray open at either end. These strips serve
two purposes:
(_a_) As the wooden roller is wider than the plank, they prevent the
coagulum being rolled too thin and too firm.
(_b_) They prevent the coagulum being squashed too wide, and tend to
keep the edges straight.
To avoid "thick ends" it is sometimes considered advisable to insert, at
either end of the rolling table, shallow wedges about 6 inches long, of the
same width as the table (between the edge-strips), and with the sharp end
of the wedge pointing in the direction of the length of the table. The ends
of the coagulum are drawn up and finished on these inclined planes.
These points may appear to be extreme refinements, but as long as rubber is
valued on such grounds we must endeavour to meet the system imposed upon
us.
Public-domain text, read in full here on John Shaqi.
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