Glaze Group Meeting

13th February 2007

Di opened the meeting with glaze samples she has produced based on Jun recipe (JB2) from Mike Bailey's Cone 6 Glazes in which she varied the amount of cobalt and fired to 1130C to get a pale green colour, but slightly different effects were obtained on a terracotta body or on Scarva Earthstone.  It was agreed that to achieve more of a blue, the titanium content would have to be adjusted and that the amount of titanium was a critical factor.  She also brought along pots with blue and turquoise glazes, also from Mike Bailey, T13 and HET1, which had worked well.

The general question of glaze application was discussed and Mike had the useful suggestion of using wallpaper paste as the medium for brush on glazes.

The glaze fault of pin holing was talked over and it was agreed that the problem often arises from dust on the green ware pot and this can be overcome by damping (one of us actually hoovers as well!!!).

Various methods of decoration were discussed including sgraffito, repeated dipping in glaze to create overlapping areas of different colours, brushing and sponging underglaze colours and oxides and the use of wax-resist to produce clean pot bases and interesting decorative effects.

Mike also brought test tiles from some variations on Mike Bailey's JB2 in which the amounts of titanium dioxide and zinc oxide were examined.  The jun effect was very critically dependent on titanium levels.  Also, the addition of 1% red iron oxide gave very strong blue/green colours.

Mike had also made some copper red reductions using silicon carbide.  These glazes need thick application and faded if the firing was allowed to soak presumably due to re-oxidation. Di is going to experiment with one of the glazes (derived from a cone 9 reduction recipe) - Pot Feldspar, 75; Ferro Frit 3110, 12; Whiting, 12; Tin oxide, 1; Copper carbonate, 0.5; Silicon carbide, 05.

Charles produced a triaxial chart showing glazes from three potters and the combining of them in varying proportions, the results of which were borne out in many neatly produced samples in muted greens and browns, some of which created wonderful tree like effects.

For next time, Charles intends to experiment with a Chinese glaze mentioned in Ceramic Review No. 223, over black and green slips and the general theme of decorating ware will be further investigated.

The next Glaze Group Meeting will be at Diana Carter's home on Tuesday 10th April 2007 at 12 noon.  Everyone is welcome.  A contribution towards a light lunch will  be appreciated.  Let Diana Carter (01962 777297) know if you plan to attend.