Atoms for Detection

FAKES & FRAUDS

Every year the art faker's job gets just a little bit harder, thanks to the development of new scientific methods for determining the real age of works of art. Now atomic energy has been called to aid, as two recent developments on the art sleuthing scene testify.

In England, Oxford University's Research Laboratory for Archaeology announced that after seven years' work, it had perfected a "thermoluminescence" technique for determining the age of any ceramic, from a 6,000-year-old potsherd to a 19th century vase. The technique employs the radiation-measuring devices used at most atomic reactors and in hospital radiotherapy departments. It is based on the fact that most mineral substances buried in the earth absorb the natural radiation given off by uranium, potassium and thorium in the earth. The rate of radiation has been relatively constant in historical times, but all absorbed radiation is released when the substance is heated.

Thus when a piece of clay is fired, its radioactivity count is reduced to zero. By reheating it and measuring the radiation given off, scientists can determine the length of time since the first firing.

In Washington, the National Gallery of Art and the Atomic Energy Commission have contributed $25,000 apiece to finance three years' research into the perfection of "atomic fingerprinting" for old masters at Pittsburgh's Mellon Institute. The technique, originally developed by Dutch scientists, consists of taking flecks of paint from genuine Rembrandts and Vermeers, then bombarding them with neutrons in a reactor in order to measure their exact chemical impurities. In time, the Mellon Institute hopes to compile a library of chemical analyses of the different types of paint used by a dozen famous artists--or at least the type of paint used in the country and period of each.

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