Last week Mick introduced us to ‘primitive clay’, a heavily grogged clay body that includes sparkly mica, and we spent about an hour sculpting tiny clay oil lamps as part of our ‘light’ theme. Working on such a small scale was a new challenge for me, but I enjoyed how fast the process was – great for making maquettes. We speeded up the drying with the aid of heat guns so we could fire the lamps in the afternoon. This caused lots of cracking but surprisingly the results stayed in one piece, proving it is possible to make and fire a piece in the same day! We woodfired the clay in a big dustbin with the addition of sawdust and copper carbonate to colour the surface, resulting in a range of smoky oranges, reds and purples. There’s definitely some of Geoff Swindell’s influence in these teapot lamp forms, but unlike his precise, colourful porcelain pots, the smoking effect makes these look like they’ve been freshly dug from the ground after being buried for centuries.
Glass millefiori took 7 mins to fuse
In a similar way to how glaze powder is fused into glass on ceramic, enamel powders are fused onto copper. The temperature however is a lot lower, any higher than 800C and the enamel starts to discolour, as I soon found out.
Before and after shaping the copper needs annealing and then plunging in cold water to cool. Gum arabic is painted onto the back of the shape after cleaning, then backing enamel is dusted on top and the copper placed in a small kiln. When opened the kiln temperature plunges and you have to keep an eye on it as it gradually climbs back up to 799C. On the opposite surface different coloured enamels are fused on in separate firings, although the process is a bit more difficult than I expected. The colours don’t behave as planned, burning out before the kiln reaches optimum temperature or leaving speckled textures (which can look nice – a bit like a dusting of snow).
I’d like to know if these copper enamels can be used on top of bisqued or glazed clay. Alternatively, perhaps panels of enamelled copper (maybe a maker’s mark) could be inlaid into the clay after firing by being stuck on, although I’d have to contest with shrinkage.