Multi-flue types were also used later, allowing greater capacity and needing peat or coal as fuel.
Methods of stacking vessels in kilns are interpreted from excavated kilns which contain partial loads, but can also be reconstructed from kiln scars on glazed pottery and kiln bars, and from the direction of glaze drips on decorated vessels.
Rural potteries probably only operated part-time and the potters were peasants who spent most of their time farming.
The similarity between Iron Age and Saxon pottery, particularly in East Anglia, can cause problems where no other dating evidence is available.
There is a large amount of archaeological evidence for the pottery industry from the Middle Saxon period onwards, in the form of products and production sites.
Inclusions in the pottery, to prevent shrinkage in the kiln, vary between geological regions.
Differences in style and fabric helps pottery specialists to identify vessels which are not of local manufacture.