Tapping Knives.—The choice of a tapping knife is a subject upon which there is much divergence of opinion. This must be so because no known knife has such apparent outstanding superior features or claims as would enable one to settle the point. Moreover, the personal factor is so large that, as far as the knives in common use are concerned, it appears to exert the greatest influence. The possibility of obtaining the ideal knife, which will go to sufficient depth into barks of varying thickness to yield the maximum quantity of latex without wounding, is quite as remote at the present time as it was some years ago. Meanwhile the search for that ideal knife continues, and occasionally one learns of the alleged merits of some new instrument which, it is said, fulfils all requirements. It is only to be regretted, both for the sake of the inventor and for the expectant buyers, that the claims always fail in some one or more particulars.

In Malaya probably the number of different types of tapping knives may amount to a half-dozen, but those most commonly in use are:

Argument on the respective merits of knives is popular, and discussion seems endless. It is claimed for the bent gouge that it is superior to the straight instrument, because, the leverage being downwards on the handle, the tendency is to lift the cutting edge upwards and out of the bark, whereas with a straight gouge the tendency is to push the knife downwards into the bark. It is claimed, therefore, that the average shavings taken off by the bent gouge should be thinner than those obtained by the use of the straight instrument.

For similar reasons it is asserted that the “Jebong” and other modifications are superior to the original form of the farrier’s knife. These points are generally accepted without great argument, but when comparisons are made between the gouge and the farrier’s knife (with its modifications) the opinions of planters are so varied and conflicting as to be almost irreconcilable. Two opinions based on experience with both types of knives are often wholly contradictory.There can be no doubt that the likes and dislikes of operative coolies have a considerable influence in determining the measure of success obtained with any one knife. Should coolies have been accustomed to the use of a particular form of instrument they become quite expert, and any proposed change creates in the minds of coolies a prejudice which is considerable in effect on the quality of the handicraft. Such prejudice may be overcome in course of time, but in the interval not a little damage may have been done in the shape of tapping wounds. So considerable is this question of personal favour that even on estates where a standard pattern of knife is issued coolies often modify that knife slightly on their own accord. Such alteration is ignored by the superintendents as long as the quality of the tapper’s work is maintained at a high standard.

Naturally there is a limit to such leniency, and this limit is soon reached in the case of knives having adjustable parts controlled by screws, or nuts and bolts, etc. Some knives of this description really merit a much wider use than is afforded them at present; but in view of the potential damage which might be done as a result of adjustments made by the coolies these knives do not become popular.

It is not proposed here to enter into a description of even recent instruments for which strong claims are being made by their inventors or vendors. If they possess the merits attributed to them they will soon find favour, as managers are always keen on studying the points of any new knife which will lead to a conservation of bark and a reduction in the number of wounds. On the whole, it may be advanced that the best general results are obtained by the adoption of a simple non-adjustable knife and the retention of its use.The Choice of Latex Cups.—It has come to be recognised that the maximum possible cleanliness is essential in all details of estate work, and the younger generation of planters could scarcely be aware that a few years ago it was deemed sufficient to use coco-nut shells for the reception of latex on individual trees.

Terne-plate cups ousted the coco-nut shell, and they had the merit of being cheap. The interior coating of tin did not last long if the cups were properly cleaned. The iron being exposed, with a minutely roughened surface, each microscopic projection served as a point around which latex coagulated. Scrapping the film of interior rubber became more and more difficult, and often the cups were burnt in order to get rid of the accumulation of rubber. The last state of such cups was worse than the preceding one. On some estates fairly successful attempts were made to keep these cups clean by making the coolies bring them into the store each day. Terne-plate cups are not now in common use.

Aluminium cups have their advocates, but much the same argument applies to the difficulty of keeping them clean as was used in the foregoing paragraph. On many estates, however, they are used with success, the usual method of treatment being to make the coolies bring them into the store and clean them there. Owing to the comparative lightness of the material such a scheme is more feasible than was the case with terne-plate cups.

The cups now most in general use are either of glass or white-ware, and probably those of glass are the most extensively employed. There are many details to be studied in the choice between these two types of cups—e.g., percentage of breakage in transport and in the field, price when breakage is taken into account, etc.; but these apart the glass cups have one advantage—namely, the ability of the superintendents to see whether the cups have been properly cleaned. In the case of white-ware cups this means an inspection and handling of individual cups, whereas in the case of glass the point is settled by visual examination at a comparative distance.

Glass cups are made in two patterns, one having a flat bottom and the other a conical base. The latter is convenient for use when wire supports are employed, the cup fitting into a loop placed beneath the spout. Used on the ground its shape is an obvious disadvantage, as, unless a hole is scooped for its reception, it has to be propped up with sticks or stones. Often a touch is sufficient to upset the balance, and latex is lost.

The flat-bottomed cup, on the other hand, may be used with success equally on a wire support or on the ground. It is sometimes said that owing to its shape the ease of cleaning, as compared with the half-spherical cup, is diminished, and that if the cups when not in use are kept inverted upon sticks placed near the foot of the tree the breakage is apt to be high. This latter objection is being rapidly removed as the practice of using these sticks is losing vogue for various reasons, and wire cup-holders will be in general use as soon as the cost of material becomes normal.

There are on the market, and in fairly wide use, cups of Chinese and Japanese manufacture. These generally consist of brown earthenware with an interior glass finish. These are cheap in comparison with glass and white-ware cups, but it is a pity that the glass does not extend over the whole of the cup. The outer surface has a tendency to collect rubber and dirt. On some few estates small china bowls or saucers are still used and are quite satisfactory, except for the favour with which they are regarded by natives on the outskirts of the estates.Cleaning Cups.—The question of cup-cleaning would appear to be a very simple one; but in practice it is quite a source of worry to managers, especially where a mixed labour force is employed. Tamil coolies can be made to clean their cups in the day’s task and at odd times. Chinese coolies, more often than not, either refuse to give the necessary attention or else demand extra pay for the work.

The method of cup-cleaning employed more popularly within recent years was that of daily washing. The tapper carried two buckets, one for receiving the latex and the other containing water. Pouring the latex in the bucket the coolie then added a little water to the cup and added these rinsings to the latex collected. The cup was next washed hastily in the bucket of water and replaced. By the time the coolie has emptied and washed some 200 cups (about half the task generally) the water has the consistency of dilute latex, and the wet cup when replaced becomes coated with a thin film of rubber. If the latex is always collected in one direction it will be clear that, while the cups at one end of the task are comparatively clean, those at the other end have the chance of being correspondingly dirty.

Controversy has raged respecting this question of cup-washing, and many estates have abandoned it as a daily practice. Coolies have not to carry an extra bucket of water. The contents of the cups are poured into the latex-bucket, and the bulk of the latex film remaining is also removed by the aid of a finger. The cup is then replaced, a thin skin of rubber forming on the interior surface. As a general rule this is easily removed on the next occasion, except perhaps in dry weather. It is the custom on most estates employing this practice to have all cups receive special attention at regular intervals.

There are certain economic factors entering into the difference of opinion regarding the two broad methods employed. In some cases—e.g., on old areas—it would be practically impossible to follow the older method of daily cup-washing, as the tappers have to employ two buckets for the collection of the latex. The employment of special coolies for cup-washing would be necessitated, such as may be seen sometimes on estates working Chinese “squatter” labour—where the man taps, a child assists in collecting, and another child, or the mother, washes the cups. It may be pointed out that in such instances the helpers are not paid by the estate. Their services merely mean a saving in time which is spent in the squatter’s garden, and perhaps the permission to the tapper to work a larger number of trees than would be allotted ordinarily to a task.

Again, on some estates, the tappers, while not being required to carry a bucket of water for cup-washing, are given an increased number of trees to tap. Furthermore, on hilly areas under tapping, it is often manifestly unfair to expect the tapper to be able to carry two buckets during collection, when the slope is such, as to make the manipulation of even one bucket a matter of difficulty.It will be seen, therefore, that there is no clear issue for argument concerning the two methods, and that the point must be decided on the economic factors peculiar to each estate or district.

Water in Cups.—Much discussion used to take place regarding the necessity or otherwise for placing a small quantity of water in the cups when tapping. It was recognised that the permission to use water (with the idea of preventing coagulation) led to much abuse, apart from the question as to the utility of the method. Dirty water was often used, although clean water may have been placed in the buckets when coolies left the muster-ground. The small quantity of water often exceeded the actual yield of pure latex by hundreds per cent., with the result that on arrival at the factory the diluted latex was below the standard desirable for the preparation of a good sheet-rubber.

Premature Coagulation.—Other opinion to the contrary it is now generally acknowledged that the possibility of premature coagulation in the cup or bucket is at least not diminished by the addition of even clean water. The use of water often obtained from estate drains clearly led to increased trouble. The extent to which such premature coagulation takes place varies greatly under the influence of many factors—e.g.:

The last mentioned factor is of great importance. As a general rule it is noted that premature coagulation is less marked on estates situated on comparatively hilly land. The greatest effect is remarked on estates situated on the flat lands of the coastal area where peaty soils are a feature. On many such estates, in spite of the observance of all ordinary precautions, it is not possible to receive the latex at the factory without a large percentage of prematurely coagulated rubber being found in the transport vessels.Anti-Coagulants.—For this reason on these (and other) estates, the use of small quantities of anti-coagulants is common. The effect of these is to keep the latex liquid and thus render possible the preparation of a higher percentage of first-grade rubber than would be otherwise obtained.Among the better known agents which have such an effect upon latex, formalin and sodium sulphite (not bisulphite) are the chief. The latter is the more popular as it is slightly cheaper and much more stable. As now used, it is in the form of an easily soluble powder (anhydrous sodium sulphite). The ordinary crystalline form of sodium sulphite as used in photography is not recommended, on account of its comparative lack of power and its poor keeping qualities.

It will be obvious that, given two equal quantities of different latices, different amounts of an anti-coagulant may be required to produce the same effect. Hence it should be remembered that a formula which suits the needs of one field or one estate will not necessarily prove suitable in the case of another field or estate. Unless this point is appreciated trouble may ensue. On some estates it has been the custom to give equal quantities of sodium sulphite solution to all coolies irrespective of the ages of the trees in the fields to be tapped. Thus it happened that the latex from one field was found to have insufficient anti-coagulant present, while that from another field could only be coagulated by the addition of an excess of acid. In this matter the experience of the preliminary trials should have caused some discrimination to be exercised as to the quantities of solution to be issued in each field or division. It has been found sometimes that a moist glossiness in the smoked sheet could be attributed to the use of an excess of sodium sulphite. Traces of the salt remained in the rubber, and as the substance is hygroscopic, moisture was being absorbed from the air, to cause a surface deposit which often returned even after the sheets were surface-washed and re-dried.

If sodium sulphite is to be used in the field, the following formula, which is in wide use, may serve as a basis for trials.

Formula for Use of Sodium Sulphite in the Field.

On some estates it is found either unnecessary or impracticable to use the solution in this manner. Instead the anti-coagulant is placed in the bottom of the bucket prior to the commencement of collection. The solution is made as in (a) above, and roughly half an ordinary latex-cupful is placed in each bucket.

Collecting Pails.—All vessels intended for the transport of latex should have a smooth and curved interior, so that cleansing may be easy. Preferably the interior and exterior surfaces should be glazed, but it is often found that the enamel chips easily, and that the handles are too frail in construction. The shoulder-pieces, to which the handles are joined, are often too lightly attached to the bucket. Something stouter in the shape of enamelled ware is required, without an appreciable increase in weight. Until such a utensil is available, the heavily galvanised and brass-bound milk-pails used on some estates are as good as anything at present in vogue, providing they are kept scrupulously clean.

The collecting pails should be kept under cover, when not in use, either at the muster grounds or at the factory. On some estates coolies are allowed to take them to their quarters, where they are used for various purposes. Curious effects of this practice have sometimes been noticed. As an example might be quoted an instance in which premature coagulation was found to take place to a surprising degree. It was discovered eventually that the coolies (Javanese in this case) were in the habit of utilising the buckets for the preparation of their food. A liquid extract of a popular fruit was often made. This extract was very markedly acid in character, and as the buckets were not afterwards thoroughly cleansed, the latex of the following day suffered.

Preferably all buckets should have a lid of slightly funnel shape. This is inverted during collection, and thus prevents much dirt falling into the latex.Payment by Result.—The arguments for and against the institution of this practice are many. In actual result there can be no question that a higher yield is obtained by the adoption of a scheme under which the coolie is either given a bonus based on result or is paid at a definite rate per pound. It is fully recognised, both by advocates and opponents of payment by result, that the personal equation of the tapper is a very important factor. A good skilled tapper will always obtain a higher yield than an ordinary individual from the same task of trees, and without any more injury to the trees. It is argued, therefore, that such an operative should be given the benefit of his skill. Apart from this, it is claimed that even the average tapper does not do his best work if he knows that he will get his daily wage, no matter what his yield may be, as long as he does not injure the trees by wounding. It is claimed that this sense of security leads to shallow tapping which, while it has an agreeable appearance, does not produce the available amount of rubber.

On the other hand, it is advanced in opposition that under a scheme of payment by result the tappers’ only consideration is the matter of obtaining rubber, and that considerable damage in the form of wounds is done by over-deep tapping. That there is a great deal of truth in these statements is not to be doubted. Much, of course, depends upon the amount and quality of the supervision possible, and upon the standard demanded. It is a notable fact, however, that on estates which first introduced the system some years ago the quality of the tapping compares favourably with that of average estates, and in a few instances within the experience of the writer the tapping is of a high standard. Possibly these are exceptional instances, and there can be no doubt that the opposition of many managers of considerable experience is founded upon the deterioration in the standard of tapping which often follows the institution of payment of tappers by result.It will be recognised by planters that apart from the personal factor in tapping, the worker might be so unfortunate as to be placed in an area from which the yield is naturally low, either by reason of its youth or from other natural causes. Obviously such individuals are entitled to special consideration in respect of the rate per pound paid for the rubber obtained. Again, on very hilly land it may be not humanly possible for a worker to tap the usual number of trees. Hence to place him on a parity with other tappers, as far as wage-earning capacity is concerned, a higher rate than ordinary must be given. It will be plain, therefore, that on any one estate it is generally impossible to set a standard rate per pound for payment by result; the rate may vary, for example, from, say, 3 cents per pound in old and high-yielding tasks to 12 cents or more per pound on young areas of the same estate.

Naturally the actual rates paid will primarily depend upon the average yield per tree or yield per acre, and the lower the average yield the higher the rates to be paid per pound. Thus, on low-yielding properties where the natural conditions render a high yield impossible the rate per pound may reach a figure of 22 cents (approximately 6d.).

The methods of arriving at the yield of rubber brought in by individual tappers vary, but broadly they fall into two classes:

Quite a number of estates which have not adopted the full system of payment by result yet employed some such method of checking the yields of individual coolies, as the observed results act as a great deterrent against various malpractices, such as neglecting to tap trees, adulteration of the latex, etc.

Tree-Scrap.—The thin film of latex which coagulates naturally upon the surface of the tapping cut after the latex has ceased to flow is known as “tree-scrap.” Normally it is collected on all estates, but the method of collection varies according to the class of labour employed. On most estates, where the labour is Tamil or Javanese, it is supposed to be removed as fully as possible before the tapping cut is reopened. The narrow strips are then placed in a bag or basket carried by the tapper. Chinese tappers usually decline to follow this practice of first peeling off the scrap, and remove it by the operation of tapping, with the result that the scrap when brought into the store has adhering to it various shavings of bark. Unless these can be thoroughly cleaned off the scrap cannot truly be classed as “tree-scrap.”Oxidation of Tree-Scrap.—It is often noted that some scrap is dark in colour, and in this condition it is generally spoken of as “oxidised” scrap. The oxidation is probably due to an enzyme, and also to the presence of chemical substances of a phenolic nature. In the course of laboratory experiments with normal latex, it was found possible to reproduce this darkening due to oxidation by the addition of very small quantities of various phenols used in general chemical processes, and the rapidity with which the darkening was effected depended upon the quantity of the phenol added. If this rapidly oxidising latex be mixed with normal latex, it would seem that the whole bulk of the latex is affected by this tendency to rapid oxidation. It is observed that this condition under which any tree may yield rapidly oxidising latex is not a permanent one.

Care of Tree-Scrap.—As these scraps eventually give a grade of rubber which compares well with other and better-looking grades care should be exercised in collection and treatment so that its quality is not impaired in any way.To Prevent Oxidation.—As a rule the scraps are picked over, and heavily oxidised pieces are sorted out; otherwise the crepe rubber prepared exhibits black streaks. The scraps should not be allowed to remain in the sun (which induces “tackiness”), and if they have to be kept over night they may be placed in a weak solution (1 per cent.) of sodium bisulphite to arrest oxidation. It should be recognised that such a solution will not “bleach” already darkened scrap-rubber, and the nature of its action is only anti-oxidant.Bark Shavings.—In the matter of collecting bark-shavings much depends upon the organisation and nature of the labour force. Probably, on the majority of estates bark-shavings are collected systematically, but on quite a number considerable laxity in this respect has been noted. This may arise from lack of adequate supervision or from the peculiar systems of working which seem to pertain to Chinese labour. Granted that the trees are well “scrapped,” and that the percentage of rubber obtained from shavings under such circumstances would be extremely small (say 2 per cent. by weight on the total output), it does not need much calculation to see that annually the loss of rubber to the estate must be considerable. It would also seem to follow that, if the adult labour declines to pick up bark-shavings carefully, it might pay to employ children for the purpose. Or, as is done in some places, the adult labour might find it advantageous to collect bark-shavings at low rates per pound.It is a well-known fact that if bark-shavings be allowed to accumulate in a heap for any but a short period, a fermentative and heating action is set up. The heat developed in these piles of shavings is so considerable that it is impossible to keep the hand in a heap for more than a second or two. Should this be allowed to persist, as would happen in the case of a breakdown of engine or machines, it usually results in the final crepe rubber becoming tacky when approaching dryness.

To avoid this heating effect it is necessary to have spare jars or proper tanks in which the shavings may be soaked in water. In this condition bark-shavings may be kept for many days.

For the same reason (i.e., the heating effect and consequent tackiness) the custom followed on some estates of allowing coolies to keep bark-shavings in their “lines” until they have accumulated a fair quantity cannot be commended, quite apart from the possibility of actual loss by theft, which is thus rendered easy.

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.