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Series editors' preface - Wood Tools

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Triterpenoids<br />

Plastics and polymers, coatings and binding media, adhesives and consolidants 177<br />

Coniferae<br />

(Araucariaceae)<br />

Leguminosae<br />

Dipterocarpaceae<br />

(Dipterocarpoideae)<br />

Juniperus spp.<br />

Cupressus spp.<br />

Agathis australis<br />

Agathis dammara<br />

(also known as A.<br />

alba)<br />

Hymeneae spp.<br />

Copaifera spp.<br />

Guibortia spp.;<br />

Tessmannia spp.;<br />

Daniela spp.<br />

Triterpenoid resins<br />

come from<br />

numerous genera<br />

of broad-leaved<br />

trees, mainly but<br />

not exclusively<br />

tropical.<br />

Approximately 500<br />

species in 15<br />

genera principally<br />

Hopea spp. and<br />

Shorea spp.<br />

Kauri copal<br />

Manila copal<br />

East African or<br />

Zanzibar copal;<br />

Brazil copal<br />

Copaiba balsams<br />

Copal<br />

Dammars<br />

sandarac soluble in alcohol but<br />

insoluble in turpentine and white<br />

spirit. Also insoluble in drying oils<br />

unless heat treated. Melting point<br />

135–145 °C<br />

May have been confused with<br />

sandarac in past<br />

Copal is a general name given to a<br />

large variety of hard resins obtained<br />

both as fossils and taken fresh from<br />

living trees. Accumulations in soil of<br />

Araucariaceae resins from Agathis<br />

(the main resin producing genus of<br />

the Southern hemisphere) gave rise<br />

to hard and durable ‘semi-fossil’<br />

resins extensively exported and used<br />

in the nineteenth century for<br />

making high quality varnish. Manila<br />

copal is described by various<br />

different names according to<br />

hardness. Fresh resin is softer and<br />

semi-fossil resin is hard<br />

Resin producing trees of the<br />

Leguminosae are tropical. Exact<br />

source of resin is often not known<br />

due to complexity of supply chain.<br />

Though difficult to distinguish one<br />

from another, leguminous copals as<br />

a group have characteristic<br />

composition which allows them to<br />

be readily distinguished from<br />

coniferous resins. Zanzibar copal is<br />

the hardest of the copals and has<br />

very high melting point 240–360 °C<br />

Very liquid resin containing<br />

sesquiterpenes<br />

Other African copals from e.g.<br />

Congo, Accra, Benguela, Sierra<br />

Leone<br />

Much more varied taxonomy and<br />

chemistry than diterpenoid resins.<br />

Triterpenoid resins are generally<br />

non-polymerizing but easily oxidized<br />

and occur in mixtures with<br />

sesquiterpenoids rather than<br />

monoterpenoids. Dammars are less<br />

yellowing than most conifer resins<br />

and more readily soluble than<br />

leguminous copals. They dissolve<br />

completely in aromatic hydrocarbons<br />

and turpentine but only partially in<br />

alcohol. Pale in colour with very<br />

good optical properties, though<br />

some yellowing does occur over<br />

time and film has a tendency to<br />

remain slightly tacky. Melting point<br />

100–105 °C. Dammars come mainly<br />

continued

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