How long does it take to make a pot?
Have you ever wondered how long it takes a potter to make a pot? Well, whilst each individual potter uses different production methods which will vary their making timelines, there are a few features common to all potters.
1. Multi-stage making process
All potters use a multi-stage making process. Due to the changing nature of clay as it dries, different processes have to be done in pottery at specific times. Attaching a handle for example cannot be done if the pot is too dry as it will crack off, or too wet as the pot needs to hold its shape when the handle is fixed on. Even if a potter makes a very simple wheel-thrown beaker, with no handles or decoration, it is likely they will still smooth the pot with a sponge when dry to remove any sharp edges before firing in the kiln.
Most potters fire their work twice, once at a bisque firing which can reach temperatures of 950oc and once again at a glaze firing after glaze has been applied. High-fire glaze firings for stoneware and porcelain can reach temperatures of 1300oc!
At Oxford Clay, we let pots dry to the ‘leather hard’ stage and then turn the base on the potter's wheel to craft the shape of the foot. We then apply the dragonfly decoration at this stage before the pot has fully dried.
2. Allowing the clay to dry slowly and evenly
Clay absolutely needs to dry slowly or it is in danger of cracking as it dries. If one area of a pot dries out before another area, forces are exerted on the clay and sections such as spouts and handles can pull away from the main pot body or cracks can appear in the rims or bases of pots. Cracks that appear when drying are almost impossible to mend so it is critical that pots are dried out slowly and evenly.
At Oxford Clay we dry our pots initially for three days inside a damp box (a plastic box with a tightly fitting lid). This allows the moisture in the clay to distribute throughout the clay evenly. After turning the base of the pot and sponging with a cellulose sponge the pots are left to dry naturally for at least a week. Pots can only be bisque fired once they are totally dry. However, in some atmospheric conditions pots can take two or more weeks to dry fully.
After pots have been bisque fired they are dipped in glaze and this is another time when pots need to be left to dry out properly. If a pot is fired with wet glaze on, problems can occur such as ‘crazing’ where the glaze cracks all over the pot. Crazing is considered a glaze fault although some potters use crazing as a decorative effect.
3. The time it takes to heat and cool the kiln
Because the kiln needs to reach such high temperatures it takes a very long time to heat up and cool down. Many large kilns take days to heat up and cool down before they can be opened. It is very dangerous to open a kiln before it has fully cooled as such high temperatures are reached inside. If a kiln is prematurely opened before it reaches room temperature, the pots inside will be exposed to cold air causing thermal shock - cracking and faults on the glaze such as crazing.
At Oxford Clay, we use a medium-sized highly energy-efficient electric kiln to fire the pots. The kiln fires to 950oc during a bisque firing and 1260oc during a glaze firing. Due to its energy efficiency, the kiln has thick, well-insulated walls and takes a long time to cool down. For example, if the kiln is switched on to a glaze firing it takes a full 12 hours to reach 1260oc and then another 28 hours to cool down enough to open the kiln.
