Potters clay, pot clay and clay for pottery all describe the same shelf: a prepared, de-aired, bagged clay body sold by weight and matched to a firing temperature. What separates one bag from another is the range it fires to, how much grog it carries and what colour it comes out, and none of those is guessable from the name.
What a prepared body actually is
Clay dug from the ground is not what suppliers sell. A commercial body is a blend of clays and minerals mixed to a consistent recipe, de-aired in a pug mill and bagged at a workable stiffness, so that every bag behaves like the last one. That consistency is what you are paying for as much as the raw material, and it is why a body carries a code such as 157-1143 rather than just a name.
Firing range comes before everything
Every supplier prints a range, usually as two temperatures. An earthenware body around 1080 to 1180 degrees, a stoneware around 1180 to 1300, a porcelain higher still. Fire a body above its range and it bloats, slumps or sticks to the shelf; fire it below and it stays porous and weak. Whatever kiln will fire the work decides the range, and the range decides the shortlist.
Grog, texture and what your hands will tolerate
Grog is fired clay ground and added back in. It reduces shrinkage, resists cracking and makes large forms possible, and it is abrasive: a heavily grogged body will take skin off your fingertips over a long throwing session. Smooth bodies are kinder and less forgiving of thick sections. Most potters end up with one of each rather than a single compromise body.
Price per kilogram, not price per bag
Bag sizes vary and so does tax treatment, which is why this site converts everything to a price per kilogram excluding VAT. On the one body priced here at more than one supplier, the manufacturer's own price is about a fifth higher than a stockist's for an identical product under an identical code. That is worth ten minutes before an order rather than after it.
Questions people ask about potters clay
What clay do potters use?
A prepared body matched to their kiln: stoneware for most functional work, earthenware for lower firings, porcelain for fine translucent ware.
Is pot clay the same as pottery clay?
Yes. The phrases are used interchangeably by buyers; suppliers list bodies by name, code and firing range rather than by either term.
How much clay is in a standard bag?
12.5 kg is the usual UK bag and is the unit this index compares. Some suppliers also sell 10 kg and 25 kg, which is why a bag price alone tells you very little.