Firing the quality debate/Pyro techniques vs advanced kiln control

摘要

Pyrometric devices have been used to in the ceramic industry for many years to measure the progress of kiln firing. Before thermocouples became available, there was no other method available to do this other than by removing a piece of ware from the kiln and physically examining it. This often resulted in ware being under or over-fired with the loss of much product. Clearly it would be of great help to ceramic manufacturers to have some method of knowing when their product had been correctly fired, and in 1782, Josiah Wedgwood published details of his invention to do this task. So the first pyrometric device was born, although Wedgwood's product disappeared in the earlyl800s. Pyrometric devices are made from ceramic materials and are designed to measure the total effects of the firing on the product in the kiln, Pyrometric devices DO NOT measure temperature. AH pyrometric devices measure the total effect of the heat energy of a kiln firing received by the product in that kiln. This is not just the maximum temperature of the kiln, but includes the time that the kiln is at the maximum temperature, the rate of temperature rise and cooling time in the initial stages, as well as the effect of kiln loading density and kiln atmosphere. This total effect is often referred to as 'heat work' although this is not the same concept as thermodynamic heat work.