What are pyrometric cones used for?

Pyrometric cones are specifically designed to assess and indicate the temperature and heat work that occurs within a kiln during firing. They are made from various ceramic materials that change their shape, melt, or bend at specific temperatures, which provides a visual confirmation of the heat conditions inside the kiln. By observing the state of the cone after firing, potters and ceramic artists can determine if the desired temperature was reached and maintained, ensuring that the clay or glaze has been appropriately fired for the intended results. This is crucial for achieving proper vitrification and glaze maturity.

The other choices do not encapsulate the primary function of pyrometric cones. Measuring colors in firing pertains more to evaluating the visual outcomes of different firing stages rather than the cone's function. Creating pottery shapes relates to the molding and forming process, which is not what pyrometric cones are used for. Designing ceramic glazes involves the formulation of materials and colorants, not the measuring of kiln temperatures. Thus, the use of pyrometric cones is uniquely associated with monitoring and assessing heat in a kiln.