What it is
Palaquium gutta and its relatives, the gutta-percha trees — evergreen trees of the rainforests of Malaysia, Indonesia, and Southeast Asia, in the sapodilla family, Sapotaceae, and so relatives of the sapotes, the mahua, and the chewing-gum-yielding sapodilla.
Like its chicle-bearing relative, the gutta-percha tree yields a latex — but a very different one, whose peculiar properties made it, for a few decades in the nineteenth century, one of the most strategically important materials in the world.
The latex that connected the continents
Gutta-percha latex, tapped and dried, is a natural thermoplastic: hard and rigid at room temperature, but softening when heated so it can be moulded, then setting hard again — and, crucially, it is tough, durable, an excellent electrical insulator, and, unlike rubber, highly resistant to seawater.
That last quality changed history. In the mid-nineteenth century, engineers were trying to lay telegraph cables under the sea to connect distant lands, and they needed an insulation that would protect the copper wire in cold salt water for years — and gutta-percha was the one material that worked. It insulated the first successful submarine telegraph cables, including the transatlantic cable that first joined Europe and North America, and it remained the standard undersea-cable insulation for the better part of a century. The Victorian communications revolution — the wiring-together of the continents into a global telegraph network — quite literally ran inside a sheath of gutta-percha. It is one of the clearest cases of an obscure tree's product enabling a transformation of the world, and the enormous demand led to the trees being tapped, and often felled, on such a scale that wild gutta-percha was seriously depleted. See restoration economics.
From golf balls to root canals
Beyond cables, gutta-percha's mouldable toughness gave it a long list of nineteenth- and twentieth-century uses: it was moulded into furniture, jewellery, picture frames, walking sticks, and countless household objects; it made the tough, mouldable core and later the whole of the early golf ball — the "guttie" ball that revolutionised golf, replacing the old feather-stuffed ball and making the game cheaper and more popular; and it was used for splints, tubing, and waterproofing.
Most of these uses have long since given way to synthetic plastics — but one endures in every dentist's surgery. Gutta-percha is still the standard material used to fill and seal root canals in dentistry: after a tooth's infected pulp is removed, the cleaned canal is packed with points of gutta-percha, whose inertness, mouldability, and stability make it ideal for the job. So a material that once wired the oceans now, most commonly, sits quietly inside people's teeth — a small, strange afterlife for a world-changing tree product. It sits alongside rubber and chicle among the great tapped-latex trees.
Growing it
Tropical, frost-tender, and a tree of the hot, wet, lowland rainforest, gutta-percha wants warmth, high humidity, high rainfall, and deep, rich, well-drained soil — true wet-tropics conditions — and it is a slow-growing forest tree.
Historically it was mostly wild-tapped (and over-cut), but sustainable production means growing it in plantation and agroforestry, tapping the latex without felling, and it is grown from seed and cuttings. Its main interest now is historical and dental rather than as a major crop, but it remains a fascinating example of how the specific chemistry of one rainforest tree can shape technology and history. See propagation and reforestation techniques.
See also
- Rubber the other great tapped-latex tree, for elastic rather than rigid latex
- Sapotes its sapodilla-family relatives, including chicle-yielding sapodilla
- Mahua another useful Sapotaceae tree
- Restoration Economics the over-tapping that depleted wild gutta-percha
- Reforestation Techniques sustainable, tap-not-fell production
- Tung and Candlenut other trees grown for industrial tree products