How to identify kiln waste, and what it can tell us

When found in the archaeological record, pottery is usually broken and in poor condition. It is therefore often difficult to ascertain when, how and why the pots were broken. One of the many reasons a pot would have be disposed of in the past was because it was a ‘waster’ from a production site. This was a product that did not satisfy high quality standards, so could not be sent to retailers, and was disposed of after manufacture. If a large quantity of pottery is found in a single context, and is within the vicinity of a production centre, it probably constitutes a pottery dump – a place in which to dispose of a large group of wasters or pieces that were broken during manufacture.

A good example of a waster is this collection of three 19th-century plant pots fused together, and recently recovered from such a dump in Yorkshire. All have a very rough fabric that has been fired to a dark purple and is slightly vitrified. Vitrification (literally, ‘turning to glass’) occurs when the clay physically melts, having been heated to a very high temperature. The inner pot (top) in the photograph had a drainage hole through the centre of the base, helping to identify it as a plant pot, and each pot had a partial name stamp impressed into the base. The inside of the vessels is misshapen and melted together, making them a good example of a production failure, having probably collapsed and fused during firing. This would imply that they were stacked together inside a kiln. The decoration was limited to a single incised line around the external body of the pots, and the consistency in design and shape indicated that they were part of a mass-production line, probably encompassing hundreds of similar examples.

The impressed stamps helped us to identify where they were made. Moreover, the presence of additional poorly made pottery (including more plant pots and cooking vessels), and kiln furniture within the same context implied that it was a pottery dump created by this production site during the 19th century. It also informed us of the types of pottery being manufactured there during that time.

In archaeology we often deal with what people have thrown away and this is a fantastic example of what a single discarded item can tell us about the past. One man’s rubbish…