Unfortunately there are no affordable direct methods for dating pigments, except in some cases as we will see later.
Generally, for example, we can’t establish when a vermilion stroke was brushed onto a painting, but we can date most of the materials that the pigments are painted on.
Therefore, in archaeology, thermoluminescence dating works best for ceramics, cooking hearths, incidentally fire-cracked rocks, and deliberately fire-treated rocks, such as flint or chert.
Measuring the intensity of the luminescence can determine how much time has passed since the last time the object was heated.
The light is proportional to the amount of radiation absorbed since the material was last heated.
The TL operator generally takes samples for dating from the bottom, avoiding damage to the image of the artwork.
TL is based on the fact that almost all natural minerals are thermoluminescent.