The test involves preparing a sample 75 mm long with a cross section of 10 mm for most ceramic products. In the white-ware industry sample bars around 50 mm long with a cross section of 3mm tend to be used for purely comparisons of clay bodies.

The test specimen is dried and then allowed to cool in a desiccator, the length measured to the nearest 0.1mm and then placed into the expansion apparatus. Malkin in conjunction with British Ceramic Research Association designed the original apparatus, which utilised a tube furnace to heat the specimen and a dial gauge to indicate the distance moved by the push rod and hence the thermal expansion. Many companies automated this original design by fitting a kiln controller to control the furnace and a linear transducer linked to a plotter to measure the expansion.

A few companies linked the transducer to data loggers, which could log the voltage output from the transducer and temperature via a thermocouple place near the test specimen (Instead of relying on the kilns thermocouple in the original design) simultaneously.

In recent years computers have been used to both control the furnace and monitor the specimens temperature and the linear movement, automatically applying correction factors and producing both a graph and a table of results.

These developments have reduced the labour involved, i.e. the original equipment needed a technician to manually control the temperature and take regular temperature and dial gauge readings.  Modern equipment utilising SCADA Monitoring and Control Systems such as in the FGH design or  S. L Electrotech’s computer controlled system take a few minutes to set up and can be left unattended.