Copal kauri

In addition to shellac a number of other natural resins find use in modem industry. They include rosins, copals, kauri gum and pontianak. Such materials are either gums or very brittle solids and, although suitable as ingredients in surface coating formulations and a miscellany of other uses, are of no value in the massive form, i.e. as plastics in the most common sense of the word. 

Other special macromolecules are known, and some were analyzed by pyrolytic techniques. Among these are special gums and lacquers such as mastic, gum elemi, copal, kauri, sandarac, shellac, colophony, amber, etc. [4]. These materials have narrow fields of applications and were not included in this book. 

CAS 9000-14-0 EINECS/ELINCS 232-527-9 Synonyms Copal (INCI) Cowrie Gum copal Kaurie Resin copal... 

Structural types from New Zealand kauri gum or copal. Kauri is the Maori name for Agathis australis (Araucariaceae), while copal is the Spanish version of the Nahuatl (Aztec) word copalli, meaning resin. Kauri gum was formerly an important raw material for the manufacture of varnish and linoleum, and it has been a valuable source of new terpenes for natural products chemists. 

Ka.un. This fossil resin, classified as a copal, is found in the South Pacific, primarily in New Zealand. It formerly was used in protective coatings. It is still used in the Kauri-butanol test (ASTM D1133) to determine the volume of thinner that can be added to a varnish formulation without causing turbidity. 

The first attempts at predicting solubility were largely empirical. Paint technologists employed various approaches. In one approach kauri-butanol values were equal to the minimum volume of test solvent that produced turbidity when added to a standard solution of kauri-copal resin in 1-butanol. The aniline point is the lowest temperature where equal volumes of aniline and the test solvent are completely miscible. Both tests are measures of the relative aromaticity of the test solvent. 

Figure 1.34 Pieces of rou and polished copal. Top, left and middle South American copal right Xew Zealand kauri bottom i it, Dominican copal.

Figure 1.36 Copal seeping on trunk of Kauri tree.

Kauri gum is of a darker colour than most copals (Fig. 1.34), and, like the Japanese copal, some of it is turning into amber. It is mosdy transparent and it contains few inclusions. Insect inclusions are extremely rare. It has been successfully worked into a variety of decorative objects and jewellery. 

Copal can be carved into figures and polished. However, copal deteriorates with age and jewellery or carvings lose their surface polish. There are carvings in existence that are many years old and do not yet show signs of deterioration, but these are made from old copal such as kauri. 

Among the copals, only New Zealand kauri is totally protected. Although it is possible to walk in the national forests where a few of the trees still grow, it is requested that the trees are not touched as this would involve treading on the delicate, shallow root system. The trees may not be felled but should a tree fall from natural causes such as a storm, both the wood and any copal found around its roots can be collected by the appropriate authorities and sold. It is thus still possible to buy small amounts of kauri copal in New Zealand. 

Our knowledge of the history of copal is also confined to one species New Zealand kauri gum. 

Japan. A varnish yielding a hard, glossy, dark-colored film. Japans are usually dried by baking at relatively high temperatures (ASTM D 16-52). True Japan varnishes contain a strongly irritating chemical, more recent types contain kauri or copal resin, linseed oil, lead oxide, pigments, and solvents such as kerosene or turpentine. 

Manila resin. A type of copal resin similar to Congo and kauri. 

A particularly common test for ranking hydrocarbon solvent strength is the kauri-butanol test. The kauri-butanol value (KB) of a solvent represents the maximum amount of the solvent that can be added to a stock solution of kauri resin (a fossil copal) in butyl alcohol without causing cloudiness. Because kauri resin is readily soluble in butyl alcohol but not in hydrocarbon solvents, the resin solution will tolerate only a certain amount of dilution. Stronger solvents such as toluene can be added in a greater amount (and thus have a higher KB value) than weaker solvents like hexane. 

USE Instead of copal, damar, or kauri in making enamels. 

Present in ma,ni1a and kauri copals. Cryst. from MeOH. M.p. 203-4. [a]o + 581 in 2tOH. Dist. —> noragathic acid + COg. Se dehydrogenation —> 1 2 5-trimethylnaphth- ene. H COOH —> iwagathic acid by further riiU closure. 

Bush kauri copal n. Special grade of the Kauri copal, which has fossilized on trees at the point of exudation and above ground level. 

Chalk kauri n. Soft, white, powdery form of kauri copal. 

Copals n. Gum resins exuded from living plants and fossilized in the ground. Some of the opals are Zanzibar, amber, kauri, Manila, and Congo. 

Fossil gum resin n. Fossil gums are the so-called hard gums or copals with were exuded from living plants in the form of liquids or semisolids, which have lain in the ground for centuries and thus hardened or fossilized with time. Some of the fossil gum resins are Amber, Zanzibar, Kauri, Manila, Pontianak, and Congo. 

Kauri kau(-9)r-e [Maori kawri] (1823) n. A fossil copal resin used in oleo-resinous varnishes found in New Zealand. Langenheim JH (2003) Plant resins chemistry, evolution ecology and ethnobotany. Timber Press, Portland, OR. Paint pigment, drying oils, polymers, resins, naval stores, cellulo-sics esters, and ink vehicles, vol 3. American Society for Testing and Material, Conshohocken, PA, 2001. 

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