Pottery fakes now easier to detect

Press, Volume CXIII, Issue 33191, 3 April 1973, Page 10

Pottery fakes now easier to detect

A report from an Oxford University [ archaeology research ' laboratory this week has disclosed that many highly priced pieces of [ T’ang dynasty (eighth century A.D.) Chinese ■ pottery circulating on the open market are fakes, made this cen-ji tury. Some of the pieces, fetch- ' ing up to £50,000, have been acquired by at least one major museum. A technique : for dating these pieces, developed by the Oxford laboratory, can prevent further mis-i taken purchasing, reports an N.Z.P.A. staff correspondent in London. Dr S. J. Fleming, who does the testing, says he is working now for all European, American, and British museums, and inspects material for all the London salerooms and art dealers. His method, called thermo- : luminescence testing, is based on the fact that the quartz and feldspar particles present in clay acquire a thermoluminescent glow from passing through the atmosphere. This glow is lost when the clay is fired, but starts reaccumulating after it has left the kiln. By accurately measuring the amount of thermoluminescence re-established in the object since manufacture, Dr Fleming can determine its date.

Dr Fleming has been using this method for four years, and has recently developed a more sensitive process that can fine down the aging to specific years. “If it was established as a forgery I could formerly say it was less than 100 years old, but now, with the more sophisticated method, I can say that it is perhaps 35 years old,” he said today. Four major pieces W'ere submitted for testing by the Freer Gallery of Art, part of the Smithsonian Institution of Washington, and two were found to be fakes. Of 37 T’Ang pieces analysed recently, he found eight to be fakes.

The best fakes circulating at present appear to have been made after a period of railway construction in China in 1910. During this time many early tombs were discovered, and ancient moulds for T’Ang pottery found. The T’Ang Dynasty is seen by Dr Fleming as one of the

most important periods of ceramic development. “The excitement generated by the quality of workmanship, both in form and colour, has spread throughout the art market and museum world alike,” he says in the report. “The inevitable reappearance of a rash of imitations, particularly at the beginning of this century, was the source | spring for the beginning of i scientific analysis, in the

[direction of glaze deterioration with age and with detailed thermo-luminescence study.” The glaze deterioration method takes account of the minute fracturing of the surface glaze on ceramics, and until the thermo-luminescence testing was developed it was the only method by which art connoisseurs could determine age — apart from any aesthetic judgment on style. However, says Dr Fleming, it is possible for an authentic T’Ang piece to show little or no “crazing” (fracturing) because of ageing, but a modern imitation may show the opposite.