- Dammar gum
Dammar gum is obtained from the Dipterocarpaceae family of trees in India and East Asia, principally those of the genera Shorea, Balanocarpus or Hopea. Most is produced by tapping trees; however, some is collected in fossilized form from the ground. The gum varies in colour from clear to pale yellow, while the fossilized form is grey-brown. Dammar gum is a triterpenoid resin, containing a large number of triterpenes and their oxidation products. Many of them are low molecular weight compounds (dammarane, dammarenolic acid, oleanane, oleanonic acid, etc.), but dammar also contains a polymeric fraction, composed of polycadinene.
It is used in foods, as either a clouding or a glazing agent, in the making of incense, varnishing and in other processes. Dammar was first introduced as a picture varnish in 1826, and is commonly referred to as dammar varnish. The varnish, made from dammar gum and turpentine is commonly used in oil painting, both during the painting process and after the painting is finished.
The name is a Malay word meaning "resin" or "torch made from resin".
There are two further types of damar, besides the gum:
- Mata kucing ("cat's eye") is a crystalline resin usually in the form of round balls.
- Batu ("stone") is the name given to the stone or pebble-shaped opaque damar collected from the ground.
- Appearance: white powder
- Melting point: approx. 120 °C
- Density (kg per m3): 1.04-1.12
- Water solubility: xylene
- Refractive index: approx. 1.5
- CAS number: 9000-16-2
- EINECS: 232-528-4
- Harmonised Tariff: 1301-90
Stability and toxicity
The gum is stable, probably combustible, and incompatible with strong oxidizing agents. Its toxicity is low, but inhalation of dust may cause allergies
- ^ Scalarone, D.; Duursma, M. C.; Boon, J. J.; Chiantoire, O. MALDI-TOF mass spectrometry on cellulosic surfaces of fresh and photo-aged di- and triterpenoid varnish resins. J. Mass. Spec. 2005, 40, 1527-1535. DOI: 10.1002/jms.893
- ^ William Theodore Brannt (1893). Varnishes, lacquers, printing inks and sealing-waxes: their raw materials and their manufacture. H. C. Baird & co.. p. 168. http://books.google.com/books?id=JMPvAAAAMAAJ&dq=dammar%20varnish&pg=PA168#v=onepage&q=dammar%20varnish&f=false.
- ^ Mayer, Ralph (1991). The Artist's Handbook of Materials and Techniques (5th ed.). Viking Adult. ISBN 0-670-83701-6).
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