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Geology for potters

I am currently writing a book on Science for Potters for the American Ceramics Society. An extract on Geology for Potters has been published in Ceramics Monthly November 2015. Many potters use locally sourced clays and rocks in their clay bodies, slips and glazes. While researching for my book, I have become interested in geology and spent part of my recent holiday in Cornwall visiting clay mines and searching for rocks. My father used to take me on rock collecting expeditions to Aust Cliff under the old Severn suspension bridge, where we found quartz crystals and fossils. Aust Cliff is composed of layers of red mudstone and limestone.  You can see in the geological map below, it is part of the Mercia mudstone red clay shale deposit which stretches from the north of England coal beds down to the south coast. I recently visited an exhibition in  National Museum Cardiff  on the geological maps of William Smith, who first realised that layers of rocks were laid down in a sequence according to the fossils embedded in them.

You can read my article here:

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Aust Cliff, photo Adrian Pingstone 2002
Map of clay deposits in UK
Map of commercial clay deposits in UK by Henry Bloomfield
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Cornish clay pits

I have been visiting clay pits in Cornwall, researching for my next book Science for the Potter. I visited three clay pits. The first was in St Erth near St Ives, a disused clay pit where sand and red clay were once dug. The pit has been turned into a nature trail but you can still see a rusted metal trolley embedded in the ground. It is very overgrown but there is still visible red clay and sand, which Bernard Leach used in his earthenware clay body.

I also visited a china clay pit, Wheal Martyn near St Austell. Unlike other types of clay, china clay is not found in an immediately usable form. It is part of a crumbly white rock, which is decomposed granite. The clay is washed out of the rock by directing a powerful jet of water onto the newly exposed rock. The water is pumped out of the mine and left to settle in tanks. The sand and mica settle out, leaving china clay, which is drained off and dried. At Wheal Martyn you can see a working pit now owned by Imerys, as well as the old settling tanks and drying sheds once used to process the china clay. There are displays of old machinery and earthenware pots made by Lake’s pottery in Truro. On the way home we stopped in Bristol, went to the Royal west of England academy of art and by chance saw the painting of The Clay Pit by Harold Harvey of the Newlyn School, painted in 1923.

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Wheal Martyn China clay pit
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Lake’s Pottery display

On on the last day of the holiday I drove to Doble’s clay pit in St Agnes. I got lost down a long rutted track but finally found the clay and sand pit with some directions from Mr Doble. I bought a bag of his stoneware clay and had a look at the clay pit, grey fireclay which lies directly under the gorse and heather on the headland near St Agnes Beacon. Doble’s has supplied the Leach Pottery with stoneware clay since the 1960s. I’m looking forward to trying the clay out with my glazes.

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Doble’s clay pit St Agnes
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Store of fireclay at Doble’s

 

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New website

Cups for NotontheHighStreet.com NOTHS

Welcome to my new website, created by my husband Henry.

Here I will be posting news and photos of what I’ve been making.

My latest commission is for new tableware for the NotontheHighStreet.com office. I am making cups and saucers, plates, teapots, jugs and bowls. NotontheHighStreet like to decorate their office with unique products designed and made by their partners. They found my porcelain mugs did not chip or break, so have ordered the whole range for their new office in Richmond.

Cups for NotontheHighStreet.com's new office in Richmond.
Cups for NotontheHighStreet.com’s new office in Richmond.