Enamelling

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.

 

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Hot melt rubber molds

I took part in my first ‘open house’ workshop today where I learnt how to use the hot melt vinyl compound Vinamold/Gelflex to make flexible moulds. Much cheaper than silicone, it can be used to cast all sorts, from plaster to wax, resins and ceramic material.However it does have some drawbacks, namely that it shrinks over time and when used with plaster or wood they have to be soaked first in water.

The Vinamold is first cut into sugar-cube sized chunks which is a bit of a challenge but is easiest done with a stanley knife and scissors. The texture is similar to that of tough meat. Next it’s heated in the microwave to around 150C which took around 6 minutes for  a full Pyrex measuring jug, a little longer for larger quantities. It’s best to check the consistency every 3 minutes or so in case it begins to burn. The objects we wanted to make moulds of were placed onto sheets of clay with a cottle to give a gap of about two fingers width in between. When the compound was of a runny, soupy consistency it was poured into the moulds and left to set for about an hour. It was easy to release the objects from inside and every tiny detail is captured. The process is so much quicker than making a plaster mould.

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