Archaeologists and Ceramic Technology
Grooved Ware pottery, like all but the very latest prehistoric pottery in Britain, was hand built and fired in open fires. It varies greatly in quality from hard, well-fired and carefully constructed to coarse, poorly fired pots that have the consistency of wet cardboard when excavated. It is possible that some pots were more carefully made as they were intended to last for a long time while others were manufactured quickly and with less care, perhaps as disposable containers for one-off events such as feasts.
Some archaeologists attempt to better understand prehistoric pottery through the study of the manufacture of pots in small-scale societies that utilise similar technology. Others undertake experimental reconstruction or apply analytical scientific techniques such as ceramic petrography (the study of the composition of rocks found in pot bodies) or residue analysis (the study of food residues found on pot sherds) directly to the ancient pots themselves.
How to make a Neolithic pot
In order to make a Neolithic-style pot it is first necessary to identify a suitable source of naturally occurring clay. These are widespread but have very different characters from place to place. The best naturally occurring clays can be of very high quality indeed while others can be difficult to work without careful processing.
It is seldom necessary to do much more than remove the larger stones and roots from the clay, although, as the following photograph illustrates, this can be a messy business! The clay can now be dried or mixed with more water to produce the best consistency for pot building.
Prehistoric-style pots can be formed from a single piece of clay or built up by the addition of further rings, coils or straps of clay. It is also possible to mould the clay over a surface or beat it into a mould. The latter two techniques are especially useful for forming the round-based pots that were commonly used before the introduction of Grooved Ware. A runny ‘slip’ of wet clay can be added to the pot if a smoother finish is required.
Once the clay has dried to the ‘leather hard’ stage it may be decorated. In the Neolithic, common decorative techniques included incised lines, marks made by impressing various objects, applied cordons of clay, and smoothing and burnishing. Recently, it has become increasingly apparent that some prehistoric pots were deliberately coloured by the addition of various natural pigments including ochre, chalk and crushed bone. The imprints of woven fabrics or baskets that supported the pots during manufacture can be seen on some sherds.
Once formed, the pots must be left to dry completely. This can take several days in a centrally heated house. In prehistoric times drying would have required warm, dry weather or placing the pots near a fire. If a pot is not fully dry before firing then the water inside the clay can boil and cause the pot to break, often quite dramatically. For this reason it is usually necessary to gently pre-heat the pot shortly before firing to ensure that all free moisture has been driven off.
Once the pots are dry it is necessary to prepare the fuel for firing. During the Neolithic this is most likely to have been wood in most parts of Britain, but others fuels would have been available, and perhaps frequently employed, in some regions. Peat appears to have been used in Orkney, for example, and dried animal dung can make a very effective fuel. Prehistoric potters would have been well aware of the advantages of different types of wood and would have developed considerable skill in controlling the fire, which would be important if the pots were not to break. For a firing to be successful it is important that there is no rain and that winds are light as sudden changes in temperature can result in cracks forming in the pots.
The preheated pots can be added to the fire before it becomes too hot. Extra fuel can then be carefully added until the temperature is high enough to drive off the chemically bonded water that air drying alone cannot remove. Once this has occurred the pots are fully ceramic and will not return to clay when they come into contact with moisture. Successfully firing pots in this way requires considerable skill.
Once fired, the pots must be allowed to cool slowly if they are not to crack. In some parts of the world skilled potters can fire large numbers of pots in open fires, but there is no evidence that this happened in prehistoric Britain. Indeed, the small-scale production of hand-built pots took place well into the 20th century in some parts of Europe. In Jutland, Denmark, for example, peat-fired ‘Jydepotter‘ were fired in pits using peat as a fuel, and hand-built pots were fired on open hearths in the Outer Hebrides within living memory.
The nature of open firing means that the colour of the pots produced can vary considerably. This is because the amount of oxygen in different parts of the fire is hard to control. Pots fired in an oxygen-rich (oxidising) environment tend to have a lighter colour than those in an oxygen-poor (reducing) environment. In is possible that in some regions attempts were made to control this process to produce particular results. It has been suggested, for example, that some Neolithic pots in Orkney were deliberately fired in a reducing environment in order to impart an attractive dark colour. Another factor affecting the colour of the pots is the nature of the clay from which they are made.
Using Neolithic Pots
Analysis of the burnt food remains found attached to prehistoric pottery can allow us to get some idea of what the pots were used for. Meat, vegetables and milk products have all been identified, although fish seems to have fallen out of favour in most parts of Britain after the introduction of agriculture. Neolithic ceramic ‘sieves’ found in central Europe are likely to have been used for the production of cheese, a suggestion backed up by recent experimental work.
It is clear from the quality of much Neolithic pottery that many potters possessed considerable skill. Other vessels, however, can be coarse and poorly fired. Why this is so is of some interest in itself as it is not hard to develop a basic level of competence in hand building pottery. Could it be that coarse pots were more appropriate for some uses than fancier, more carefully made vessels? Questions such as these will form one aspect of the Tracing the Lines research. If you would like to see how this progresses do keep an eye open for future additions to this blog.