Although the export price had risen to £61 a ton in 1900, good-quality gum was harder to find, and a market therefore developed for the poorer grades, used in the manufacture of linoleum. Fluctuations in export quantities, rather than prices, were noticeable over the next 20 years. The drop to 4,500 tons exported in 1915 was a result of the restricted European market during the First World War. In 1920 the United States bought 3,244 tons as against the United Kingdom's 2,544 tons, the average value being £86 a ton. Export prices dropped to £25 a ton during the depression of the thirties; and although unprecedented values were reached in the forties (£101 a ton in 1948), demand for gum became less. Quick-drying synthetics had superseded kauri gum in the manufacture of varnish. Substitutes were also used in linoleum manufacture, and low-grade gum failed to interest overseas buyers.

Since 1947, “range” or “pale” gum from high localities has been exported for use in the dental trade. One ton shipped to England in 1962 realised more than £300. This market takes only “bold” gum – clean pieces with the outer coat removed. There has been a revival in the use of “brown” gum, from swamps and low-lying ground, due to a demand from the United Kingdom, U.S.A., Italy, Germany, and Sweden. The last three countries use it in varnish.

The supply of fossilised kauri gum is not exhausted. Lumps are often turned up when new land is developed, and good-quality gum can bring a high price.

In 1961, 91 tons of kauri gum valued at £13,183 were exported; the 1964 exports were 53 tons valued at £11,481.

by Jeanne Hannington Goulding, Botanist's Assistant, Auckland Museum.

• Diary (typescript), Hobbs, J. (1848)
• Researches in Geology and Natural History, Darwin, C. (1839)
• The Gumdigger, Reed, A. H. (1948)
• New Zealand or Recollections of it, Markham, Edward, McCormick, E. H. (ed.) (1963).