In the case of wandoo both wood and bark were chipped and extracted with water to form a concentrate of 60-63 per cent tannin. A plant established in 1934 produced about 6000 tonnes per year of tannin for a time, for use both in leather tanning and later as a viscosity modifier in oil well drilling muds, but because of competitive pressures it closed down in the early 1960s.

Today there is no significant production of tannins from forest resources in Australia, domestic requirements being supplied either by the synthetic tanning materials which have been developed overseas since the Second World War or by imports of wattle bark extracts from South Africa, derived from plantations of the very species which were once the basis of our own tannin industry. Tannin-formaldehyde waterproof adhesives, developed by CSIRO[73] in the 1950s and 1960s and used in plywood and particleboard manufacture, are now also based on imported wattle bark tannins.

The thermal decomposition of wood to produce charcoal and volatile products (wood tar, 'pyroligenous acid' and gases) is a very old technology. Many small bush kilns operated in Australia in the 19th and early 20th centuries to produce charcoal, mainly for use as a clean fuel but also for a wide range of other uses including ferrous metallurgy and gunpowder manufacture. A few plants of more modern design still operate today using sawmill waste.

There was little interest among the earlier plants in recovering the volatile products from charcoal production. In 1907, however, the Melbourne-based chemical and fertilizer manufacturer, Cuming Smith and Co., established a plant near Warburton, Vic. to produce both charcoal and chemicals from the extensive mountain ash forests in the area. Their technology was based on European practice and the primary products recovered were charcoal, wood tar and creosote, methanol and calcium acetate. Some methanol was converted to formaldehyde and the calcium acetate to both acetic acid and acetone. About 20 000 tonnes of wood was used annually. There seems no doubt that at that time the technology was 'state of the art' and product costs and markets favourable. After the First World War, however, the market for charcoal declined and lower cost processes for acetic acid, acetone and methanol manufacture came into use, leading to closure of the plant in 1924.

In 1948 a plant to make wood charcoal from eucalypts for high grade iron and steel production was established at Wundowie in Western Australia. Initially volatile products were also recovered but this was later discontinued as it was not economically attractive. Charcoal was produced up until the early 1980s, when a decline in demand led to temporary closure. There are, however, plans to resume operations to make charcoal for use in silicon production.[74]

Australian Academy of Technological Sciences and Engineering