Dammar gum

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, , oleanane, , etc.), but dammar also contains a polymeric fraction, composed of .^[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 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[]

Fresh dammar gum consists of a mixture of compounds; primarily , , and . ^[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.CS1 maint: numeric 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.