lab in Oxfordshire. We must first prepare it for measurement when we receive your sample.

<P> lab in Oxfordshire. We must first prepare it for measurement when we receive your sample.

TL screening process

What exactly is Thermoluminescence?

Whenever a little test of ancient pottery is heated it glows with a faint blue light, referred to as thermoluminescence or TL. The pottery absorbs radiation from its environment and it is this which creates thermoluminescence during its lifetime. The older the pottery, the greater amount of radiation it’s consumed as well as the brighter the pottery test glows. By calculating the TL, we could calculate just exactly just how much radiation has been absorbed and employ these records to determine the approximate chronilogical age of the pottery.


Powder examples

Powder examples (from pottery and bronze cores) are blended with acetone and permitted to settle, in order that fine grains, approximately 1/100mm. diameter, are chosen. These grains are dried and deposited onto aluminium discs (for fine-grain analysis) or rhodium (for pre-dose analysis). Any staying powder is dried out and employed for radioactivity dimensions to perform the calculation that is dating.

Porcelain cores

Porcelain cores are glued into slim tubes that are hollow. As soon as the glue is dry, these are generally cut into pieces 1/4mm dense with a fine diamond blade.

The blade is water cooled to avoid overheating. Each slice is wet in acetone after cutting to eliminate the glue. Pieces are then prepared for TL dimension. The rest of the core is crushed and employed for radioactive analysis to accomplish the calculation that is dating.


We now have 3 completely automatic, computer operated Riso Minisys TL visitors for calculating the TL. Test discs are installed on a wheel and also the visitors are programmed to perform heating and irradiation sequences. The TL is calculated making use of painful and painful and sensitive detector called a photomultiplier tube. The amount that is total of the pottery has absorbed during its life time may be determined through the TL. The dose that is annual of radioactivity in the pottery could be calculated within the laboratory utilizing counters. From all of these dimensions we could get an approximate age for the piece.

Fine Grain technique

The examples are heated while the information seems as being a graph of TL against heat, called a glow-curve.

The examples are irradiated in the laboratory having a understood radiation dosage and heated to produce another glow-curve. By comparing the glow-curves we are able to determine the dosage of radiation consumed by the piece during its life time. Radioactive measurements in the clay informs us just just how much radiation the piece gets every year. This gives us to determine the approximate chronilogical age of the piece. Using TL we are able to observe that one of these brilliant ‘fat women’ is genuine together with other is really a contemporary content.

Glow-curve from genuine Fat Lady

Glow-curve from modern Fat Lady

Both for pieces: curve (a) may be the TL emitted by an example of powder obtained from the thing, curve (b) is really a laboratory induced glow-curve curve (c) may be the back ground. The ancient piece : (a) is means over the background (c), and approximately midway between history and (b) the current piece : (a) is simply right above the back ground (c) and method below (b)

The Pre-dose Method

Porcelain and particular other forms of clay can not be tested utilising the fine-grain technique. We then need to use the method that is pre-dose. The TL audience is programmed to determine alterations in the 110 o C top of quartz (the pre-dose top) when you look at the clay. Every time the sample is irradiated and then heated, the pre-dose top increases. The rise is associated with radiation dose. The very first increase is because of the natural dosage that the piece has consumed over its life-time. The test will be offered a laboratory irradiation and a 2nd enhance is calculated.

because of these dimensions we could determine the chronilogical age of the piece.

Glow bend from ancient piece

Glow bend from contemporary piece

The black colored bend is the backdrop (base-line) measurement The red and blue curves would be the archaeological TL signals The green bend is through the used laboratory dose For the genuine vase, the archaeological signal(s) are very well over the history and near the sign through the used laboratory dosage. For the contemporary vase the archaeological sign is scarcely above back ground and well below the TL signal from the used laboratory dosage.

TL minerals in ancient pottery radiant since they are heated