How we date a pot without a label

Most pots in the stores came to us without any paperwork at all (sample story).
Curators start with the clay: valley clay fires a warm orange, river clay a grey brown. The shape narrows things down, and the soil around a find, if anyone recorded it, can place it within a century.
Come to the curator’s tour on Thursday to see how three of the jars in Rivers of Clay were dated.