Ruthanne Tudball's
Soda Firing Weekend
Reviewed by John Allam

On the coldest, wettest June Friday imaginable four of us met at Meri and Steve's to load hundreds (and hundreds and hundreds) of pots into the woodfiring 'Joe Finch' kiln - now looking a little motheaten after birds have raided the ceramic fibre cladding for nest building. Ruthanne arrived in the evening slightly gob smacked at the density of packing. An ex-Californian, she has lived in Britain since her late teens.

Bricking up the door of the kiln

After an overnight warm up with a gas burner, stoking began in earnest at 10 am. Rotas of volunteers kept the wood steadily entering the fireboxes under the direction of Steve and Ruthanne. Approximately 1 kg of soda had been well dispersed in small glazed dishes between the pots (NB. not biscuit-it melts under the soda), and sets of cones and draw rings ( high silica clay) were placed accessibly to ports in the door. Using only two or three pieces of wood at a time the temperature was kept rising steadily, but at 1200o C the temperature appeared to be sticking. Checking the cones revealed this to be a pyrometer problem. A delicate balance between reduction firing from 1000oC, and temperature rise followed with Ruthanne now controlling the firing, giving a convincing impression of a Hollywood version of a NASA countdown. Steve was now obviously wanting to be involved but graciously was backing off-every 20 minutes! Between 1260oC-1280oC, 1 1/2 kgs of soda painted onto the fuel was added and at 1280oC, a soda solution (1/2 kg) was regularily sprayed into the kiln. Overall 3kgs of soda was needed. A soak at 1300oC for 45 minutes completed the firing in the early evening. Steve then disappeared to start cooking goulash for the assembled company.

The weather throughout the firing had been dry but very windy, but it decided to start to rain as the firing finished.

Stoking the kiln

On Sunday morning, Ruthanne showed slides illustrating the development of soda glazing over the years principly from German 13/14th century. Bellamine, it was suggested, owed their origin to the Green Man. The survey continued with a sample of contemporary sodium glazed ware and some shots of kilns- and their interiors.

In the afternoon, Ruthanne showed her throwing techniques ending with a teapot thrown off the hump, spout first, a handle ring, lid thrown right way up and finally the body. Other pieces were heavily facetted with bamboo harps with very heavily crinkled wire.

Finally Sunday ended with the opening of the kiln. The main thing about the firing was the wide range of results, both in the amount of reduction evident and the sodium flashing. This was almost certainly owing to the weather conditions and the density of packing. Your commitee were obviously too generous in the number of pots allowed to each participant. Due note has been taken.

Ruthanne Tudball - 'Dancing Vase'

Tips:

• Read Nils Lou's book 'The Art of Firing', explaining all that happens inside the kiln.
  
• Always wad the pots: 3-1 alumina and china clay. Pea sized wads, as many as necessary, for pots and kiln props. Also cockle shells packed with wadding can act as pot props also.
  
• Paper or thin wood inserted into a kiln-catches fire in and oxidising atmosphere, smolders in reduction.
  
• Reduction firing-black smoke not necessary and shows a waste of fuel. If smoky flame emerges then pulls back into the kiln when spyhole brick is withdrawn-that's enough.
  
• Always protect kiln with furnacecote.

This was a fascinating and informative weekend which Ruthanne's personality and knowledge kept continuously lively-in face of everything a British summer could throw at us! Potters really must be crazy.