Kilns and Firing Schedules Questions and Answers

Answer: A

Correct answer: heat work, combining temperature and time

A cone bends when it has received enough thermal energy, which depends on how long it was held as well as how hot it got - the same integrated effect the ware itself experiences. That is why a cone is a better guide to whether a firing is complete than a thermocouple reading, which reports only the instantaneous temperature and says nothing about the soak.

Answer: B

Both are true and the reason gives the difference: a slow firing reaches a given cone at a lower temperature than a fast one, so the two instruments are answering genuinely different questions. Both are used, since each answers something the other cannot.

Answer: C

One and a half tonnes out of a total of 3.5 is about 43 per cent. Proportions of this order are why lightweight furniture is worth its considerably higher cost per piece. Furniture cost is set against fuel saved over many firings.

Answer: D

The time spent at temperature matters as much as the peak itself, which is what heat work describes. A brief touch at peak and a long soak give quite different degrees of vitrification. Schedules therefore specify holds as well as peak temperatures.

Answer: A

A green piece is too fragile to dip in glaze and would soften in the slurry. The biscuit fire consolidates it while leaving it porous enough to absorb the glaze readily. Biscuit temperature is chosen for handling strength and porosity together.

Answer: B

Correct answer: Both A and R are true, and R is the correct explanation of A

Both are true and the reason gives the purpose. Biscuit firing is deliberately stopped short of vitrification so the ware remains porous; the glaze slip is then applied and the porous body sucks the water out of it, leaving an even coating that dries and holds. A fully vitrified body would not absorb, and the glaze would run or fall off. The glost firing then goes higher and matures both glaze and body.

Answer: C

Single firing, or fast-fire once-firing, applies glaze to dried green ware and fires both at once. It saves an entire kiln pass but demands closer control of the body and glaze together. Body and glaze must now share one schedule rather than two.

Answer: D

Correct answer: a complete kiln cycle and its fuel

Single firing takes the ware from green to finished in one pass, so it saves the entire biscuit cycle - its fuel, its kiln time and the handling between the two firings. The difficulty is that the glaze must survive the burnout of water, binder and carbon happening beneath it, so the process demands a well-matched body and glaze and a carefully controlled schedule.

Answer: A

Iron and copper compounds take quite different colours depending on their oxidation state, which is the basis of celadon and copper red glazes. The atmosphere is controlled by restricting air rather than by adding anything.

Answer: B

Copper gives green in oxidation and red in reduction, and iron behaves similarly. Atmosphere is therefore part of the glaze recipe rather than a separate matter of kiln operation. Atmosphere is specified alongside the recipe for such glazes.