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http://www.russellkingstonceramics.co.uk/
Russell Kingston makes Devonshire Slipware (roots in medieval North Devon). Slip is dipped, poured, brushed, trailed and splashed with animated movements. Colour is achieved using oxides in slips. The terra cotta pots are then fired in a large homemade gas kiln in oxidation about 1100c (cone 03).
These pieces are said to be "freshly slipped". Clearly, it is necessary to stand clear when this is being done! The white is first applied by dipping and the brown decorative elements are added using trailing, dripping and splashing techniques. The thixotropic nature of the thickly applied slip is very evident, were it not for this gravity would quickly kill the design. The slip is mostly plastic ball clay, it slowly dries until reaching the same water content as the body. The body and slip then dry and shrink as a unit. The mix of feldspar and ball clay have the natural consequence of being thermal expansion compatible with the body (since their mineralogies are similar). At low temperatures the firing shrinkage of neither is very high so that, coupled with the thinness of application, permits their fired union. Photo courtesy of Russell Kingston, Lynmouth Slipware Pottery.
These thickly applied clay slips are defying gravity! This piece has just been engobed using a thixotropic brown slip. The white was applied over that by pouring and the decoration done by scoring and dripping. Both slips are very high in ball clay, no additive is necessary to make them thixotropic. The gelled state persists even with double or more the amount of water that would be in a glaze slurry. The rheology of both of these slurries, the brown underlayer and of the white overlayer, is the entire secret of how this is even possible. People who want to understand why things work come to digitalfire.com, one reader said the following about this page: "Thank you SO much for sharing this information, I have been searching for exactly what you are talking about here!" Photo courtesy of Russell Kingston, Lynmouth Slipware Pottery.
The traditional UK slipware is possible because of the brilliant gloss and hyper transparency of glaze made using lead bisilicate frits. The lead glaze interacts with the colors in underlying slips, dissolving and feathering them (as enabled by the time and temperature of the kiln). Interactions with iron produce warm colors. Ware is bisque fired after the decorating and drying (lower left), then dipped in the leaded glaze. Photo courtesy of Russell Kingston, Lynmouth Slipware Pottery.
Made by Russell Kingston, Lynmouth Slipware Pottery.
Glossary |
Slipware
Slipware, in the UK, is terra cotta pieces decorated at leather hard with thixotropic high ball clay slips, then bisque fired and clear glazed with lead bilisicate. |
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