Producing resins

Accroides, Congo, damar, boea, elemi, kauri, mastic and other commercially valuable resins are exudations of a variety of trees and shrubs in many parts of the world. Their industrial applications range from adhesives and incense through inks and oilcloth to textile sizing and wax compositions.

Arabic, tragacanth, ghatti, karaya and other commercially valuable gums are also exudations of a variety of trees and shrubs. Their hydrophilic and other properties render them useful in the adhesives, beverage, cosmetic, paint, paper-making, pharmaceutical, textile and other industries.

Many of the resins or resin-like substances of the Mediterranean and adjoining regions have been exploited by man from the earliest times. Good examples are myrrh and frankincense with their Biblical associations and purposes. Some were used by the Egyptians in embalming, while mastic and sandarac have long been valued for special paints and varnishes. In the Middle Ages the famous Italian painters made use of them, the actual formulae used being sometimes closely guarded secrets.

Resins are an abundant and varied resource in the wet tropical forests of Southeast Asia. These exudates have been found archaeologically in Malaysia and are still exploited extensively by indigenous peoples. For example, resins are a component of the torch technology of the Semelai of Tasek Bera.

Resin tappers in Sumatra induce resin flow in Shorea javanica (Dipterocarpaceae) by first opening vertical rows of small (3cm) holes in the tree trunk. After 6-12 months, larger (10-15 cm) holes are opened between the rows of small holes for resin harvest. Informants reported that opium applied to trees increased resin yields. Application of 10% 2-chloroethylphosphonic acid to artificial trunk wounds of S. javnica production trees increased resin yields by 110%. Wounds of previously untapped trees exuded no resin in response to the same treatment.