Examples of thermoluminescence dating
Thermoluminescence emits a weak light signal that is proportional to the radiation dose absorbed by the material. The technique has wide application, and is relatively cheap at some US0–700 per object; ideally a number of samples are tested. The destruction of a relatively significant amount of sample material is necessary, which can be a limitation in the case of artworks.
The heating must have taken the object above 500° C, which covers most ceramics, although very high-fired porcelain creates other difficulties.
Different materials vary considerably in their suitability for the technique, depending on several factors.
Subsequent irradiation, for example if an x-ray is taken, can affect accuracy, as will the "annual dose" of radiation a buried object has received from the surrounding soil.
For artworks, it may be sufficient to confirm whether a piece is broadly ancient or modern (that is, authentic or a fake), and this may be possible even if a precise date cannot be estimated.
To put it simply, certain minerals (quartz, feldspar, and calcite), store energy from the sun at a known rate.
This energy is lodged in the imperfect lattices of the mineral's crystals.
Thermoluminescence dating (TL) is the determination, by means of measuring the accumulated radiation dose, of the time elapsed since material containing crystalline minerals was either heated (lava, ceramics) or exposed to sunlight (sediments).
As a crystalline material is heated during measurements, the process of thermoluminescence starts.If you can measure the rate of acquisition of the stored energy, you can figure out how long it has been since the exposure happened.