U3A learn all about pottery

COMMUNITY group U3A of Westbury met at the United Reformed Church Hall on Tuesday 10th July, where they were joined by Trevor Pictor from White Horse Pottery.
Margaret Skyrme reports, “We met on a hot sunny afternoon and welcomed Trevor Pictor from the White Horse Pottery. Unfortunately he was unable to bring his wheel with him on this occasion, but promised a return visit.
“He did however bring some clay and several pots, illustrating the process from start to finish. Trevor explained that being a potter is a challenging job and one of the oldest, being mentioned in the Bible. Wiltshire has a lot of clay and the type of clay affects what can be made. He uses earthenware clay which he obtains from Stoke on Trent and comes from river bed sedimentary rock.
“A pottery at Dilton Marsh ran until the 1950s, which then ran out of the potting-type clay and could only make bricks and tiles from local clay. We heard that apprentices first learned to make a straight-sided cylinder and then progressed to adding a handle.
“The resulting pot is air-dried to obiscuito stage before the first firing. The pots are subsequently dipped in glaze, which comprises white clay with added titanium, zinc or borax for example, which affects the colour, as does the colour of the clay. The second firing then takes place.
“Firing is a risky process as temperature is critical and the kiln cannot be heated too quickly as the rate of shrinkage needs controlling. Trevor went on to illustrate what happened when one of his kiln burners failed. It led to an interesting result when the glaze slipped. The amount of organic matter in clay also affects the end result when the gases given off blow through the glaze. Crackle glaze happens when clay and glaze shrink at different rates.
“Who would have thought that potting was such a precarious process? Trevor was asked various questions and the gardeners amongst us were interested to learn why terracotta pots often crack and break during the winter. Terracotta is fired at a lower temperature and are porous, so that during a wet winter with periodic frosts, the water freezes and expands, causing the pots to fail. This is aggravated if they are also filled with wet compost.
“The White Horse Pottery is situated in the oldest school building in Westbury and one or two of our members remembered attending school there. Matravers School also used to hold classes there and for a time it was also a youth centre.
“It was an interesting and entertaining afternoon where we learned about pottery and a little more about one of our town’s older buildings. We all enjoyed refreshments afterwards and look forward to Trevor visiting us again.
“We have a canal trip in August and return to the United Reformed Church hall on 11th September at 2pm when a representative from the Salisbury Arts Trust will talk about the history of hospitals in Salisbury.”