Store-Rooms for Rubber and Storage.—The question of storage of rubber in factory buildings has always possessed importance, but has demanded increased consideration recently.
From experience in this country, it is clear that cement floors for store-rooms or packing-sheds are the least suitable. They are often visibly damp, especially in the early morning. To allow rubber, packed or unpacked, to remain upon a cement floor in the tropics, is to court trouble from moulds, external or internal. If the employment of a cement floor is unavoidable, the rubber and boxes should be raised on wooden supports, giving a clearance of at least 3 or 4 inches, and there should be clear ventilation space between tiers of boxes.
Experience indicates that the best type of floor is that already advised for sorting and packing rooms—i.e., a good hard timber floor raised at least 3 feet above ground-level. Apart from the advantage in labour specified in the previous paragraphs, this provision of ample ventilation space below the floor is a great consideration in the preservation of the timber. Raised store-rooms become essential in low-lying districts which are at all subject to flooding, yet the writer has seen many boxes of rubber damaged by flood-water entering a packing-room situated on the level.
The question has often been raised recently as to the length of the period during which rubber may be safely stored in this country. The answer can be only supplied by experience, of which up to the present we have none possible of being classed as reliable. Whatever storage may have been done in the past has been influenced greatly by the unsuitability of the storage accommodation, and the fact that often the rubber was not prepared with a view to prolonged storage.
While the market demand was strong, rubber was being shipped and passed into circulation, at a rate which did not demand investigation of the subject of local storage. In the year 1918 conditions were such as to bring the matter into prominence, and we were able to tender advice on the lines given in this chapter. The necessity passed, but has again arisen.
Our experience goes to prove that if rubber is properly prepared and thoroughly dried before packing, it will remain in good condition for a period of a year or more in this country. How much beyond a year it may be kept remains to be determined. The assumption of “proper preparation” leaves great room for reservations.
In the case of crepe rubbers, there is no great difficulty, provided that the recognised methods and formulæ are employed, and that the rubber is packed only when perfectly dry. Under those conditions, the higher grades of crepe remain apparently unaffected on storing. Any appreciable deterioration may be attributed to defective preparation or external causes, such as accidental damage by water.
The prolonged storage of lower grade rubbers is attended by more risk, especially in the case of the lowest grade (earth-scrap) from estates which neglect the practice of regular and frequent collection of the raw product. The same reservation applies to crepes made from tree-scrap which is not collected daily. In these types of crepe rubber “tackiness” may be initially present only in small degree, but the final damage may be immensely greater by close contact of the folded rubber during prolonged storage.
When we come to discuss the possibility of storage of smoked sheets, the difficulties become immensely greater. We have yet no reliable experience as to the keeping properties of this grade when properly prepared, fully cured, correctly packed, and stored under the best of local conditions. It is understood, of course, that in the qualification by the term “local” conditions, we assume it to be more difficult to store rubber generally in Malaya than in a temperate climate. The average temperature and humidity of the atmosphere are here much more favourable to the development of mould growths than would be the case, say, in Great Britain.
In discussing this question, as far as it refers to the preservation by storing of smoked sheet rubber, it is not fair to draw conclusions as to the likely behaviour of packed rubber from data based upon observation of loose specimens. We have samples of smoked sheets prepared in 1910, and these, superficially, appear to have remained unchanged. No mould is present and, as far as intermittent observation enables us to judge, moulds have never been incident. Whether such rubber would have been preserved in this condition had it formed part of a packed case, is a point upon which we have no experience; neither can we give any opinion. It seems true, however, that loose specimens “keep” better than bulk samples of the same preparation.