It will be clear that where the trees are scrapped efficiently before tapping, the amount of rubber to be obtained from the treatment of pure dry shavings would be almost nil, and would scarcely repay the cost of collection and working. In actual practice, however, it is not possible to guarantee that the shavings are free from some scrap-rubber. Shavings brought in by Tamils and Javanese carry only a small amount of rubber, whereas where Chinese tappers are employed the yield of rubber may be as high as 35 to 40 per cent. upon the total weight of the material treated.
Few estates now are not equipped with “scrap-washers“—machines specially designed for removing the bark from the rubber—and if they function efficiently the resulting crepe should be free from bark-particles.
Collection of Earth-Scrap.—This, the lowest grade of rubber, is found at the base of the tree. Theoretically, if proper precautions are observed, the amount should be comparatively small, but in actual practice it may be very appreciable. The usual contributory causes are:
(a) Failure to replace cups beneath the spouts of trees which continue to drip latex after collection.
(b) Collection of latex at too early a stage.
(c) Failure on the part of the tapper to ensure the flow of latex, by means of the spout, into the cup.
(d) Flowing of latex over the edge of the cut before it reaches the vertical channel.
(e) “Wash-cuts” on wet days, when the volume of rainwater down the tree is sufficient to wash the latex out of the cup.
The amount of earth-scrap collected on any estate will depend, all other things being equal, upon the labour expended in its collection. Certainly on well-organised estates, having ample labour, the amounts collected are huge in comparison with other estates. The ground at the base of the tree below the latex-spout is systematically turned over with pointed sticks and large clots of rubber are often picked up. Here, again, it is advised that the collected earth-scrap should not be allowed to remain in heaps upon the floor of the factory. It should be placed in suitable tanks containing water, and quite a considerable portion of the cleansing work is thus taken from the machines.