Thermoluminescence dating

Thermoluminescence (TL) dating 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. 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 US$300–700 per object; ideally a number of samples are tested. Sediments are more expensive to date. 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 500C, which covers most ceramics, although very high-fired porcelain creates other difficulties. It will often work well with stones that have been heated by fire. The clay core of bronze sculptures made by lost wax casting can also be tested.