Glaze Group Meeting

14th February 2005

The meeting opened with Anne's continued trials of John Britt's oilspot glaze (recipe on page 17 of the February/March 05' issue). It was useful to see the comparison between the reduced and oxidised 1260 C firings, all other aspects of body and application of glaze being identical.  The oilspots were more pronounced on her piece.  Anne maintains that a thickish application is necessary.  She will continue with more reduction firings.

Charles had raw glazed 2 small bowls (black slip on the outside) with his artificial ash glaze, modified to include 20 Hymod SM ball clay without changing the molecular composition of the glaze.  Results were satisfactory apart from slight lifting of the glaze on the outside of one pot during glazing due to the clay having been bone dry instead of leather-hard.

Raw glaze composition:  whiting 9.8, china clay 2.9, dolomite 13.7, flint 25.5, nepheline syenite 11.8, hymod SM 20.6, bentonite 2.0, soda ash 7.8, bone ash 4.9, red iron oxide 1.0.

Thermocouples were discussed and the possible inaccuracies in registering realistic temperatures when beginning to wear.  Charles said he  had spoken with Clive Shellard of Environmental Instruments in Bath, who said that any changes are likely to be negligible.  Thermocouples can be made to order to suit particular voltages by Environmental Instruments (01225 8334247) who also repair kilns and instruments.  See advertisement on Newsletter page 4.

Mike brought along several extremely successful crystalline pots fired in an electric kiln.  The process involves rapid cooling from top temperature to 1000C followed by a complicated cyclic heating.  He had used stoneware clay and a white slip to enhance colour response and minimize iron content showing through his glazes.  His slip recipe:  china clay 80 and ball clay 20.  The results with his first recipe containing 5% titanium and lithium failed with crystals being destroyed.  However, the following recipe:  ferro frit (3110) 43, zinc 28, silica 28, lithium carbonate 3.75, china clay 1 (2) and fired to 1230C proved to be rich with crystal growth.  See illustration on front page.  Oxides used were iron oxide 3% and .3% cobalt carbonate.  He will continue the process using slip again with different oxides. 

Before closing Derek Emms (who died in 2004) was remembered, having given the Southern Ceramic Group a demonstration in the past.  Several of his beautiful teapots and other pots were examined.

Charles agreed to bring his homemade sieves 60s, 80s and 100 next time.

Glaze Group meetings are held at the home of Diana Carter on the second Tuesday of every other month. The next meetings will be on the 12th of April 2005 at 12 noon.  Bring a contribution to a potter’s lunch and please let Charles Stileman (01794 340193) or Diana Carter (01962 777297) know if you are coming.