How to fire copper into clay pottery

Updated February 21, 2017

People have created unique pieces of pottery for centuries. Chinese potters used copper for creating smoked-in designs in their raku pottery. With the invention of gas and electric kilns, artists can create spectacular effects using copper with the clay pottery. The copper is heated in the kiln creating a huge range of reds, yellows, oranges, blues, greens and violets.

Copper sulphate method

Coat the kiln with a fresh coating of kiln wash, and coat a kiln shelf with a thick coating of kiln wash. Let the kiln dry overnight.

Put on a face mask. Start by mixing your coating using one of the following mixtures. For the easiest coating, mix 250 ml (1 cup) of copper sulphate into the jar of clear glaze. Another mixture combines 250 ml (1 cup) of copper sulphate, 250 ml (1 cup) baking soda, 250 ml (1 cup) sea salt, and 125 ml (1/2 cup) copper carbonate and 125 ml (1/2 cup) titanium dioxide. Mix this together in a glass mixing bowl. Use a wooden spoon and mix the solution outside or in a well-ventilated area. Pour the mixture into a glass mason jar, and cover the top with a small glass saucer.

Paint the bisque piece with a thin coating of either one of the copper sulphate mixtures. Wrap horse hair, raffia or cotton thread around the painted piece. Let the pot dry for at least four hours before firing. Do not let any of this mixture get onto the metal parts of the kiln, or it will ruin it.

Put the shelf with the kiln wash coating into the bottom of the kiln, and place the painted bisque piece on the centre of the shelf. Close the lid, and fire the kiln to 870 degrees C (1,600F) for one hour. Each kiln is slightly different. If you have a kiln with a digital setting, set it for 870 degrees C (1,600F), and start timing once it reaches this temperature. If you have a manual kiln, fire it for five hours.

Turn off the kiln, and let it sit for 24 hours before opening the lid. Once you open the lid, you see a beautiful multi-coloured fired piece. The chemicals, natural materials and copper produce spectacular results.

Copper metal method

Coat the kiln with a fresh coating of kiln wash, and coat a kiln shelf with a thick coating of kiln wash. Let the kiln dry overnight.

Paint bisque with thick coatings of clear glaze. Let it dry for one hour between each layer. While the last layer is wet, wrap copper wire around the piece, and push small chunks of copper into the glaze. Let it dry overnight.

Put the coated kiln shelf into the kiln. Put the bisque into the kiln on the shelf, and fire to the cone recommended by the glaze manufacturer. A low-firing glaze works fine for this process. Let the ceramics sit in the kiln overnight. Remove when cool. The piece will have lines of blues and greens running where the copper was wrapped.

Things You'll Need

  • 450 g (16 oz) clear glaze
  • 250 ml (1 cup) copper sulphate
  • 250 ml (1 cup) baking soda
  • 250 ml (1 cup) sea salt
  • 125 ml (1/2 cup) copper carbonate
  • 125 ml (1/2 cup) titanium dioxide
  • Glass mixing bowl
  • Glass saucer
  • Glass mason jar
  • Copper wire
  • Copper pieces
  • Horse hair, raffia or cotton thread
  • Face mask
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