Gutta-percha

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Gutta-percha is a name for a set of trees, mostly of the genus Palaquium, noted for their latex, or the rigid natural latex produced from the sap of these trees, particularly from Palaquium gutta.

Palaquium gutta

Heavy use of gutta-percha during the second half of the 19th century, particularly as insulation for underwater telegraph cables, led to unsustainable harvesting and a collapse of the supply.[1]

The word 'gutta-percha' comes from the plant's name in Malay, getah perca, which translates as "percha sap".

Taxonomy[edit]

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

In Australia, gutta-percha is a common name specifically used for the tree Excoecaria parvifolia, which yields an aromatic, heavy, dark-brown timber. It is also called "northern birch". This particular species is not related to the Palaquium genus.

Gutta-percha tree

Chemistry[edit]

Chemically, gutta-percha is a polyterpene, a polymer of isoprene, or polyisoprene, specifically (trans-1,4-polyisoprene). The cis structure of polyisoprene is the common latex elastomer. While latex rubbers are amorphous in molecular structure, gutta-percha (the trans structure) crystallizes, leading to a more rigid material.

Chemical structure of gutta-percha

Uses[edit]

Electronics[edit]

Gutta-percha latex is biologically inert, resilient, and is a good electrical insulator with a high dielectric strength. 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 rubber prior to the discovery of vulcanization.

By 1845, telegraph wires insulated with gutta-percha were being manufactured in the United Kingdom. It 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 a major constituent of Chatterton's compound used as an insulating sealant for telegraph and other electrical cables. Polyethylene's superior insulative property has displaced it.

Dentistry[edit]

The same bioinertness that made it suitable for marine cables also means it does not readily react within the human body. It is consequently used in a variety of surgical devices and for dental applications during root canal therapy. It is the predominant material used to 'obturate', or fill the empty space inside the root of a tooth after it has undergone endodontic therapy. Its physical and chemical properties, including but not limited to its inertness and biocompatibility, melting point, ductility, and malleability, afford it an important role in the field of endodontics.

Other[edit]

In the mid-19th century, gutta-percha was also used to make furniture, notably by the Gutta-Percha Company (established in 1847). Several of these highly ornate, revival-style pieces were shown at the 1851 Great Exhibition in Hyde Park, London. Molded furniture forms, emulating carved wood, were attacked by proponents of the design reform movement, who advocated truth to materials. It was also used to make "mourning" jewelry, because it was dark in color and could be easily molded into beads or other shapes. Pistol hand grips and rifle shoulder pads were also made from gutta-percha, since it was hard and durable, though it fell into disuse when plastics such as Bakelite became available. Gutta-percha found use in canes and walking sticks, as well; in 1856, Representative Preston Brooks used a cane made of gutta-percha as a weapon in his infamous attack on Senator Charles Sumner.

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.

Cultural references[edit]

Gutta-percha was featured in the pilot movie for the original 1968 Hawaii Five-O television series, "Cocoon". The primary antagonist, Wo Fat, used gutta-percha to seal the eyes, nose, and ears of victims during interrogations.

In an episode of The Wild Wild West, "The Night of the Kraken", gutta-percha was used to create a mechanical sea monster.

The Russian author Dmitry Grigorovich's 1883 story "The Gutta-Percha Boy" ("Guttaperchevyi mal'chik") is about a poor eight-year-old orphan, Petya, who becomes a circus performer. He is nicknamed the Gutta-Percha Boy because of his extraordinarily flexible joints, and plunges to his death during a performance in front of children from a well-to-do family. Two film versions have been made of the story in Russia (in 1915 and 1957), and the soubriquet "Gutta-Percha Boy," referring to someone who is unusually bendy, gained use in Russia well beyond the fame of the author.

In the novel Five Weeks in a Balloon by Jules Verne, the balloon is coated with gutta-percha.

See also[edit]

References[edit]

  1. ^ Tully, John (2009). "A Victorian Ecological Disaster: Imperialism, the Telegraph, and Gutta-Percha". Journal of World History 20 (4): 559–579. doi:10.1353/jwh.0.0088. 

External links[edit]