Pottery clay, priced per kilogram and matched to the job

Printed prices, verified

Four questions that pick a clay body

1. What temperature will it be fired to?. This is the first filter and it is absolute. An earthenware body fired to stoneware temperature bloats and slumps; a stoneware body fired to earthenware temperature stays porous. Every supplier prints a firing range and it is the number to match first.
2. Throwing, hand building or sculpture?. Throwing wants a smooth or lightly grogged body that stays plastic. Hand building and sculpture want grog, which is fired clay ground back in: it reduces shrinkage, resists cracking and makes a large form possible at the cost of being hard on your hands.
3. What colour do you want out of the kiln?. Wet clay colour tells you nothing. A grey body fires white, a brown body fires red, and the supplier's own fired sample is the only reliable guide. Buy a single bag before a pallet.
4. How much at a time?. Every supplier here prices down with quantity, steeply. One page in this index prints a per-kilogram figure that falls by more than half between a single bag and a tonne, which is the strongest argument in pottery for buying with other people.

The same body, two prices

Potclays and Bluematchbox both sell Draycott White Stoneware under the manufacturer's own code, 157-1143. Potclays prints its 12.5 kg bag at 14.76 pounds excluding VAT, which its own page renders as 1.18 pounds per kilogram. Bluematchbox prints the same bag at 12.00 pounds excluding tax, which is 0.96 pounds per kilogram.

That is a gap of about a fifth on an identical product, and the dearer of the two is the company that makes it. Nothing about that is visible to a buyer reading either page on its own, which is the reason this index exists.

Reading a price list that is not in your unit

Bag sizes are not standard and neither is tax treatment. A price that looks low may be a 10 kg bag; a price that looks extraordinary is usually a single kilogram; a trade list excluding VAT should have a fifth added before it is compared with a retail price that includes it.

The worst trap is the word from. One supplier in this index prints from 3.00 pounds on a product page whose options run from 1 kg to 500 kg, and that figure is the single-kilogram rate rather than the bag rate. Taken as a per-kilogram price it would make that supplier three times dearer than it is.

Dry clay, powdered clay and the dust rule

Wet clay in a bag presents no inhalation risk. Powdered and dry clay, grog and glaze materials are respirable crystalline silica, and this is the one part of the hobby where the precaution is not optional: mix powders with a fitted respirator, in a space you can ventilate, and wet-clean everything afterwards.

The duties written into OSHA 1910.1053 and the COSHH regulations fall on employers rather than on a publisher or a hobbyist, which is exactly why the practice is stated here rather than assumed to be understood.

Common questions

What clay should a beginner buy?

A smooth or lightly grogged stoneware in a 12.5 kg bag, matched to whatever kiln will fire it. It throws, it hand builds, it forgives, and it is the cheapest class per kilogram on most price lists.

Where is the cheapest place to buy clay?

On the one body this index prices at more than one supplier, the stockist is cheaper than the manufacturer. That will not be true of every body, which is why the table shows the date each price was read.

What is grog?

Fired clay, ground and added back into a body. It reduces shrinkage and cracking and makes large or heavily worked forms possible; it also makes the clay abrasive to throw.

Does clay go off?

No. It dries out, and dried clay is reclaimed by slaking it in water and drying it back to a workable stiffness. Clay kept in a sealed bag improves with age.

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