Gutta-percha
Scientific classification
Kingdom: Plantae Division: Magnoliophyta Class: Magnoliopsida Order: Ericales Family: Sapotaceae Genus: Palaquium
Species
About 100-120 species, including: Palaquium amboinense Palaquium barnesii Palaquium bataanense Palaquium beccarianum Palaquium borneense Palaquium burckii Palaquium clarkeanum Palaquium cochleariifolium Palaquium dasyphyllum Palaquium ellipticum Palaquium formosanum Palaquium galactoxylum Palaquium gutta Palaquium herveyi Palaquium hexandrum Palaquium hispidum Palaquium hornei Palaquium impressinervium Palaquium kinabaluense Palaquium lanceolatum Palaquium leiocarpum Palaquium lobbianum Palaquium luzoniense Palaquium macrocarpum Palaquium maingayi Palaquium merrillii Palaquium microphyllum Palaquium obovatum Palaquium obtusifolium Palaquium ottolanderi Palaquium philippense Palaquium pseudocuneatum Palaquium pseudorostratum Palaquium quercifolium Palaquium regina-montium Palaquium ridleyi Palaquium rioense Palaquium rostratum Palaquium semaram Palaquium stellatum Palaquium sukoei Palaquium sumatranum Palaquium tenuipetiolatum Palaquium walsurifolium Palaquium xanthochymum

Gutta-percha (Palaquium) is genus of tropical trees native to southeast Asia and northern Australasia, from Taiwan south to Malaya and east to the Solomon Islands. It is also an inelastic natural latex produced from the sap of these trees, particularly from the species Palaquium gutta.

The trees are 5-30 m tall, and up to 1 m trunk diameter. The leaves are evergreen, alternate or spirally arranged, simple, entire, 8-25 cm long, and glossy green above, often yellow or glaucous below. The flowers are produced in small clusters along the stems, each flower with a white corolla with 4-7 (mostly 6) acute lobes. The fruit is an ovoid 3-7 cm berry, containing 1-4 seeds; in many species the fruit is edible.

Uses

The latex is bioinert, resilient, and is a good electrical insulator, albeit with poor capacitance. The wood of many species is also valuable.

Western inventors discovered the properties of gutta-percha latex in 1842, although the local population in its Malayan habitat had used it for a variety of applications for centuries. Allowing this fluid to evaporate and coagulate in the sun produced a latex which could be made flexible again with hot water, but which did not become brittle, unlike unvulcanized rubber already in use.

By 1845 telegraph wires insulated with gutta-percha were being manufactured in England. Gutta-percha served as the insulating material for some of the earliest undersea telegraph cables, including the first transatlantic telegraph cable. Gutta-percha was particularly suitable for this purpose, as it was not attacked by marine plants or animals, a problem which had disabled previous undersea cables.

The material was quickly adopted for numerous other applications. The "guttie" golf ball (which had a solid gutta-percha core) revolutionized the game. Gutta-percha remained an industrial staple well into the 20th century, when it was gradually replaced with superior (generally synthetic) materials, though a similar and cheaper natural material called balatá is often used in gutta-percha's place. The two materials are almost identical, and balatá is often called gutta-balatá.

The same bio-inertness property that made it suitable for marine cables also means it does not readily react within the human body, and consequently it is used for a variety of surgical devices and for dental applications including padding inside fillings or inside the root-canal.

External links

• Gutta-percha on the Transatlantic cable site (http://collections.ic.gc.ca/cable/gutta.htm)
• on plastics-museum.com (http://www.plastics-museum.com/materials/naturals/gutta.htm)

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