Dating techniques for pottery
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In all, close to two dozen physical quantities must be accurately measured to establish the relationship between doses of different kinds of radiation and light output, and to compute dose rate.
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.
It was employed in the 1950's as a method for radiation dose measurement, and soon was proposed for archaeological dating.
These use pottery of the appropriate period to construct objects.
Unfortunately, it is not possible to achieve this precision for the majority of art objects.
Among the reasons for this is the small amount of material that may be taken for testing.
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.
Much stoneware is not so hard as porcelain and may be sampled by drilling.