Capsule firing

The capsule firing is a firing method that is only used for firing the glaze (smooth firing) for the firings that retain the shape. Any other firings (preliminary firings) do not require the encapsulation of the porcelain bodies. In the refinement of porcelain by e.g. reactive glazes, which are produced in the reduction process, the capsule firing is a component of the refinement technique.

In porcelain production there are basically two different types or functions of capsule firing

• reactive capsule fire
• productive capsule firing

In order not to drive this commodity knowledge endlessly into the depths, here is a brief explanation. The reactive capsule firing is intended to cause a certain reaction, e.g. the targeted increase (e.g. in the decoration firing) or the lowering (in the glost firing) of a reductive increase. The addition of boron, for example, can prevent a grey or black tint on the glaze caused by carbon monoxide. This special protective property was especially valuable in the time when porcelain kilns were still heated with coke or coal.

Reactive capsule firing always takes place in closed firing capsules. Productive capsule firing is mainly used to achieve better, i.e. higher utilisation of the firing space in the kiln and is usually carried out in open firing capsules.