Firing Day!

Wednesday 28th May 2014

Today was decoration and firing day – what a great day!  As with every other day in the project it was fast, busy and inspiring.

The morning was devoted to decorating our now fired sculptures with underglaze colours before taking some, glazing them and Raku firing them in the afternoon.  My van was packed and ready…..

During our initial planning meetings for the project, the teachers expressed a desire to use colour within the ceramic pieces.  I am also very aware that to create colour within ceramics usually come with significant cost – this is one of the primary reasons that schools find ceramics so hard to include within the curriculum.

I included the use of underglazes in our budget strategy  – not to create blocks of flat colour (this would miss the point in creating texture) but to use them to enhance the texture on the surface of the pieces while reflecting the colours of the seascapes and geology we experienced on our field trip.

The underglazes were diluted and then painted on before being gently sponged off – this creates an ‘inked’ surface which really emphasises the surface texture.  A clear raku glaze will ‘fix’ the underglazes in place during the firing….

Huge thanks to the teachers at St Machar Academy for firing 50 x pieces in the school kilns within a 6 day turnaround in the lead up to the raku firing!

After all the pieces were decorated, I set up the kiln in a secluded space behind the art department and glazed 6 pieces with the clear and copper blue raku glazes.  After lunchtime pupils congregated around the kiln for a safety prep talk and an explanation of the process.

Pupils had the opportunity to see right into the kiln while it was firing and throughout 2-3 passes of the kiln, saw the glaze surface change from dry and grey to shiny and clear.  Perhaps most importantly, we perfected our marshmallow toasting skills and avoided any mishaps by not dropping any into the firing kiln! Very soon, the kiln was ready and the pupils were moved back to a safe distance for the opening of the kiln…

Here are the main events of an outdoor raku firing:

• The  outdoor gas kiln is fired to approx 950-1000C so that the glaze melts
• Gas is turned off and the lid is lifted off
• Molten work is then removed from the kiln using large tongs and placed into a metal bucket containing wood shavings/ combustable material
• Cue big flames…
• A helper sprinkles wood shavings onto the work in the metal bin to ensure good smoke coverage
• The sudden drop in temperature causes the glaze to crackle
• The smoke created within the metal bin permeates through the crackles in the glaze
• A reduction atmosphere within some parts of the combustion process can create colour changes within some glazes eg: copper can turn from blue to red/ metallic.
• Pieces are cooled and cleaned with scrubbers

Once again we had the weather on our side and we all had a great and informative afternoon.

I now have all of the pieces at my workshop, where they will be raku fired and cleaned, ready for the exhibition at the Sir Duncan Rice Library at Aberdeen University in June.