Glazed Over

The first firing that our mugs experience is called the bisque or biscuit firing. For our mugs this means a maximum temperature of 1200^oC and an overall firing time of twelve hours. During this firing the mugs will shrink to 85% of their original size and be transformed from soft, breakable clay to hard biscuit ware that rings like a bell when tapped. At this point, the pure white translucency that fine bone china is known for becomes evident.

The mugs are then put through a vibro which is a large vibrating container filled with ceramic pellets. The pellets rub against the mugs and smooth them to give a good surface for the glaze to adhere to. The mugs are then ready for the glaze to be applied.

The glaze is a liquid that contains very finely ground glass and is applied by dipping the mugs into the glaze, the excess is then removed by shaking. The mugs are then put through a gas-powered drier to remove as much of the liquid as possible. After passing through the drier, the base of the mugs is rubbed on a sponge belt to remove a ring of glaze round the foot. If this glaze is not removed the mugs will stick to the kiln truck when fired in the kiln.

The mugs are then given their next firing which is known as the glost firing. This firing takes the mugs to a maximum temperature of 1000^oC and has an overall firing time of twelve hours. Whilst in the kiln, the finely ground glass in the glaze melts and flows together to give a smooth shiny surface.

After cooling the mugs are inspected and are ready for the next process which is decorating.

That means we’re coming to the end of the making of our mugs! Stay tuned for the final steps!