It was employed in the 1950's as a method for radiation dose measurement, and soon was proposed for archaeological dating.By the mid-1960's, its validity as an absolute dating technique was established by workers at Oxford and Birmingham in England, Riso in Denmark, and at the University of Pennsylvania in the U. The Research Laboratory for Archaeology at Oxford, in particular, has played a major role in TL research. It is an absolute dating method, and does not depend on comparison with similar objects (as does obsidian hydration dating, for example).
The age of the pottery, in principle, may then be determined by the relation Age = Accumulated dose / Dose per year Although conceptually straightforward, TL has proven to to be far from simple in practice.
Should I be concerned about artificial irradiation? If the radioactivity of the pottery itself, and its surroundings, is measured, the dose rate, or annual increment of dose, may be computed.
These will give an authentic date for a bogus object.
It must be realized that TL dating is but one of the criteria for judging authenticity.
A leaflet from Daybreak describing the TL technique in more detail and giving a bibliography will be provided to interested persons.
The phenomenon of thermoluminescence was first described by the English chemist Robert Boyle in 1663.The TL laboratory at Daybreak was established in 1977 to make TL available to the art community in general. Studies at Oxford back in the 70s on Romano-British pottery indicated that when all quantities entering the age equation are measured, the TL date of a single potsherd will typically fall within 15 per cent of the known date.When dates of a number of sherds associated together are averaged, the error is reduced typically to 7-10 per cent. The succeeding 30 years, and increased understanding of the dosimetry, have not brought much improvement. Warning about fakes using ancient materials What about airport x-rays and radiography? Thus, when one measures dose in pottery, it is the dose accumulated since it was fired, unless there was a subsequent reheating. When pottery is fired, it loses all its previously acquired TL, and on cooling the TL begins again to build up.Unfortunately, it is not possible to achieve this precision for the majority of art objects.