A soak, or hold, is a period in a firing when the kiln is held at a set temperature instead of rising or falling. Potters soak at the top of a glaze firing so the glaze can smooth out, and at low temperatures to dry work.
What Is Soak?
Kiln controllers let you add a hold to the end of any segment. A short soak at peak temperature, often 10 to 15 minutes, gives a glaze time to melt fully, release bubbles and heal pinholes, and evens out the temperature across the kiln so pieces in cool spots get closer to the same heatwork.
Longer or hotter soaks add heatwork, which means witness cones bend further and glazes can run more. That is why a hold is part of the firing plan, not something to add casually to an existing schedule.
At the start of a firing, a soak below the boiling point of water, called candling, lets damp work dry out safely. During cooling, a drop-and-hold, where the kiln falls a little below peak and holds, can give smoother glaze surfaces or grow crystals in special glazes.
Glaze makers and kiln manufacturers often suggest hold times for their products, which are a good starting point.
This pottery glossary entry from Le Studio Art Space is general educational content. Always follow the clay, glaze and kiln makers’ data for your own materials and equipment.