Dammar gum

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Dammar resin

Dammar, also called dammar gum, or damar gum, is a resin obtained from the tree family Dipterocarpaceae in India and East Asia, principally those of the genera Shorea or Hopea (synonym Balanocarpus). Most is produced by tapping trees; however, some is collected in fossilised form on the ground. The gum varies in colour from clear to pale yellow, while the fossilised form is grey-brown. Dammar gum is a triterpenoid resin, containing many 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.[1] The name dammar is a Malay word meaning ‘resin’ or ‘torch made from resin’.[citation needed]

Uses[edit]

  • Dammar varnish, made from dammar gum dissolved in turpentine, was introduced as a picture varnish in 1826;[2] commonly used in oil painting, both during the painting process and after the painting is finished.[3] Dammar varnish and similar gum varnishes auto-oxidize and yellow over a relatively short time regardless of storage method; this effect is more pronounced on paintings stored in darkness than with works on display in light due to the bleaching effects of sunlight on the colorants involved.[4]
  • Batik is made from dammar crystals dissolved in molten paraffin wax, to prevent the wax from cracking when it is drawn onto silk or rayon.[citation needed]
  • Encaustic Paints are made from dammar crystals in beeswax with pigment added. The dammar crystals serve as a hardening agent.[5]
  • As caulk for ships in the past, frequently with pitch or bitumen.[6]
  • As a common mounting material along with canada balsam for preparing biological samples for light microscopy.[7]

Constituent Compounds[edit]

Fresh dammar gum consists of a mixture of compounds; primarily Hydroxydammarenone, Dammarenolic acid, and Oleanonic aldehyde. [4]

Material safety[edit]

Physical data[edit]

  • Appearance: white powder
  • Melting point: approx. 120 °C
  • Density: 1.04 to 1.12 g/ml
  • Refractive index: approx. 1.5
  • CAS number: 9000-16-2
  • EINECS: 232-528-4
  • Harmonised Tariff: 1301-90}}

Stability and toxicity[edit]

The gum is stable[citation needed], probably combustible and incompatible with strong oxidising agents. Its toxicity is low, but inhalation of dust may cause allergies.

Other Types[edit]

There are two further types of dammar, besides the gum:

  • Mata kucing (‘cat's eye’) is a crystalline resin, usually in the form of round balls.[citation needed]
  • Batu (‘stone’) is stone or pebble-shaped, opaque dammar collected from the ground.[citation needed]

See also[edit]

References[edit]

  1. ^ 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
  2. ^ William Theodore Brannt (1893). Varnishes, lacquers, printing inks and sealing-waxes: their raw materials and their manufacture. H.C. Baird & Co. p. 168.
  3. ^ Mayer, Ralph (1991). The Artist's Handbook of Materials and Techniques (5th ed.). Viking Adult. ISBN 0-670-83701-6.
  4. ^ a b Dietemann, Patrick; Higgitt, Catherine; Kälin, Moritz; Edelmann, Michael J.; Knochenmuss, Richard; Zenobi, Renato (January 2009). "Aging and yellowing of triterpenoid resin varnishes – Influence of aging conditions and resin composition". Journal of Cultural Heritage. 10 (1): 30–40. doi:10.1016/j.culher.2008.04.007.
  5. ^ 1895-1979., Mayer, Ralph (1991). The artist's handbook of materials and techniques. Sheehan, Steven. (Fifth edition, revised and updated ed.). New York. ISBN 0670837016. OCLC 22178945.CS1 maint: numeric names: authors list (link)
  6. ^ Burger, P.; Charrié-Duhaut, A.; Connan, J.; Flecker, M.J.; Albrecht, P. Archaeological resinous samples from Asian wrecks: Taxonomic characterization by GC–MS. Analytica Chimica Acta. 2009, 648, 85-97. doi:10.1016/j.aca.2009.06.022
  7. ^ "The microscope. Simon Henry Gage. Comstock Publishing Company, Ithaca, Philadelphia". The Anatomical Record. 5 (12): 562. December 1911. doi:10.1002/ar.1090051205. ISSN 0003-276X.

Further reading[edit]