Wednesday, 20 May 2015

Neolithic Carinated Bowl: complex simplicity

At first glance a Neolithic carinated bowl, the earliest type of pottery in Britain, looks like a very simple pot. Certainly they were hand formed often from very coarse natural clay, to function as humble cooking pots. In fact when making an average sized bowl, up to about 20cm in diameter, its form flows almost naturally from the process itself. The curve of the bowl nestles nicely in the hand, the concave form of the upper body conforms to the curve of the thumb, while the fingers stretch down inside to push out the carnation.  All well and good, but when one comes to make a bowl as big as the one I made for Stonehenge, it's a different matter.  For a start there's the weight; at over thirty centimetres in diameter it requires nearly five kilos of coarse clay in its construction. This makes it virtually impossible to hold the soft vessel in one hand.  If I start building on a base (flat stone, grass mat whatever is handy) this gives it a flat base, which can only be expanded out once the clay has stiffened.  Alternatively working into the base of an old broken pot does allow one to make a round bottomed piece but only to a predetermined form and, as clay shrinks on drying it will easily release from its "mould" but will also be considerably smaller than the former.  Once the pot becomes firm enough to support itself it can be picked up and worked on but this brings with it its own problems, the stiffened clay becomes brittle, the least deformation of the rim and the pot will crack, a flaw which, in the firing, could result in total failure.  One possible solution to this is to add organic fibrous material which will act as reinforcement in the unfired pot and one of the most suitable sources of this is animal dung. Finally, once the pot has reached a leather hard stage, the entire inner and outer surfaces need to me slip coated by rubbing with a wet hand and finally burnished all over, again without putting undue stress on the rim.

Firing small pots in an open fire is a relatively simple matter provided a strict set of rules are adhered to, a large pot on the other hand is quite a different matter. That pot needs to be absolutely dry before it comes anywhere near to a flame. In a Neolithic hut it would undoubtedly have spent several days on the outer edges of the hearth, occasionally being turned to present a new face to the warmth of the fire.  Only once the potter was certain that all moisture had left the clay would the firing process begin: The pot would be moved a little closer to the fire, inverted, and with its rim supported on three stones a few embers from the fire would have been pushed underneath its dome, their rising smoke and heat filling the vessel. Replenishing and increasing this small glowing fire over the next couple of hours the potter would have carefully and steadily raised the temperature until, at around about 400 degrees C the organic matter in the clay would have begun to burn, turning the outer surface of the pot dark brown or black.  This would also be an indication that it was ready to move to the next stage of firing, surrounding the pot with embers and eventually immersing the pot into the fire, bringing up its temperature until at seven or eight hundred degrees, in the darkness of the hut interior it could be seen to glow deep red. The firing complete, the fire would have been allowed to burn down and go out and the pot would have been cooled while protecting it from sudden cold draughts that might cause it to crack.

Simple as that!

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