Dammar gum

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

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 artwork 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

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

Material safety

Physical data

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

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

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]}

References

^ 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.
^ Mayer, Ralph (1991). The Artist's Handbook of Materials and Techniques (5th ed.). Viking Adult. ISBN 0-670-83701-6.
^ ^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.
^ 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. {{cite book}}: |last= has numeric name (help)CS1 maint: location missing publisher (link) CS1 maint: multiple names: authors list (link)
^ 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
^ "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.