- Chapter Nineteen -
evidence for kiln furniture and/or kiln superstructures further strengthens the
argument that the vessels were open-fired in bonfires, as in the previous two millennia.
Finds of this nature are rare. Despite a growing body of evidence for regional
ceramic manufacture (Peacock J 968, 1989), production centres are elusive, presumably
leaving few tangible archaeological traces. The discovery of the Durotrigian sites
can most probably be seen to be a direct result of the industrial nature of the manu-
facture of Durotrigian and later Black-Burnished Wares exploited by the Roman
invaders (Gillam 1957).
Despite the lack of archaeologically recognized manufacturing sites, open-firings,
as mentioned above, can be attested by the ceramics themselves, which are often
blotchy in their surface colouration, ranging from red to black. This uneven
surface colour is a distinctive characteristic of open-firings and is a direct result of
the constantly changing atmospheric conditions within a bonfire which are difficult
to control (Woods 1989). Generally, an open-fired vessel will be basically yellow, red
or brown in base colour as the iron oxides in the clay oxidize in the firing process.
However, some portions of the pot may be subject to different firing conditions,
depending on their contact with smoking flame, partially burnt wood or burial in
ash. These portions will tend towards a grey or black colour, giving the vessel a
blotchy appearance (see Gibson and Woods 1990: 44-56; Woods 1983, 1989).
SURFACE TREATMENTSThe ways in which the surface of a vessel may be altered or modified are, on prehis-
toric ceramics, fairly limited, comprising generally colouring, addition or extraction
of clay or the raising or compression of the surface to a greater or lesser extent.
Though usually decorative, not all surface treatments need to be entirely so. Raised
or applied cordons or the roughening of the surface using incision or impressed
decoration may be purely functional, allowing better and safer handling of the vessels.
This said, the majority of surface treatments on iron age ceramics are decorative, often
elaborately so, even imitating the fine metalwork of the later phases of the period
(Grimes 1952).
Uniformity of colour of open-fired vessels is difficult to achieve and, in instances
where this uniformity is found, it is usually a result of a distinctive surface treatment
such as a slip, a pigment such as haematite or the coating of the vessel in carbon by
smoking or smudging after the main firing process. Once more Durotrigian
and Black-Burnished Ware ceramics can be quoted as an example of this post-firing
treatment. At the firing site, Farrar (1976: 50) noted that the water sherds were
'black-burnished ware oxidised tile-red to light grey'. As a result of the difficulties
in producing a uniform surface colour in a bonfire and from the presence of red
wasters, Farrar concluded that the blackening process may have been a secondary
technique.
Slip, a suspension of clay in water, appears to have been comparatively little
used in iron age ceramics. However, pigments do seem to have been employed,
particularly in the cases of haematite bowls. The bright red colour of some bipartite
furrowed and cordoned bowls of later bronze age and early iron age Wessex (Avery332