A survey was conducted on the traditional method used for resin tapping Dipterocarpus kerrii by the 'orang asli' (indigenous people) of Tasek Bera and Buloh Nipis in Pahang, Peninsular Malaysia. The 'orang asli' use the oleoresin for caulking boats, for torches and for medicinal and other minor purposes. The method used was crude, leading to the destruction of wood and to low yield and poor quality of resin. It involved cutting a rectangular hole (24×7 cm and 18 cm deep) in the stem, with a floor sloping downwards (and inwards) away from the mouth, forming a deep container in which exuding resin could accumulate. The injury stimulated resin flow but this was increased by setting fire to the hole (immediately after it was made) for about 5 min. Resin was collected after a week and then firing was repeated and resin left to accumulate for another week. The process was repeated until no more resin was produced, and then a hole was made in another part of the stem. The tapping technique was improved (in studies carried out at the Forest Research Institute Malaysia) by applying the bark-chipped method with a sulfuric acid spray as stimulant. The method is described in detail. It involved removing the outer rough bark about 50 cm above ground (diameter 100-120 cm) to provide a smooth tapping surface in which an inner bark streak about 2.5 cm wide was removed to expose the wood. The width of the tapping face was about equal to the diameter of the tree at 100 cm height, and the streak was directed upwards at a 30° angle to the horizontal. Nails were used to attach an apron and spiral gutter to the bark just below the tapped area and a cup was attached (supported by nails) as a collector. Sprays of 2.5-50% sulfuric acid were applied as stimulant and a plastic sheet was attached to the top of the tapping area to minimize contamination by rain water and other material. The optimum concentration of acid (stimulating maximum resin flow) was 10%. This method proved to be both advantageous and economical since a minimum concentration of aqueous sulfuric acid solution could be used to produce as good a yield of resin as that produced by the traditional method, but with a better quality and less damage inflicted on the tree.
