Glaze Group Meeting

9th March 2006

The Glaze Group meet every two months on the second Tuesday of every other month at Diana Carter's house at Dell Croft, Hensting Lane, Owlesbury, near Winchester from 12 noon to 2pm.  It is an interesting and sociable occasion, starting with an American lunch, which gives us a chance to get up to date and get to know new members.

Next comes the practical part.  This month (March) Di Wren brought some glaze samples using vitreous slips.

The base recipe for vitreous slip is:

Ball Clay   50, China Clay 50 Or same clay as body 100, Lead Bisilicate 11.

This produces a white slip.  Di had added 7% cobalt carbonate; and 11% copper oxide to produce blue and green slips.

Fired under a clear earthenware glaze, this produced clear bright colours.

Clear earthenware glaze - 1120 - 1150 C

Lead Bisilicate 60, Potash Feldspar 30, China Clay 6, Whiting 4.

She had also used a transmutation glaze over the same slips, with interesting results.  It was decided to experiment with these glazes at different temperatures and bring samples to the next meeting.

1.  Potash Feldspar 40, Dolomite 8, Whiting 22, China Clay 20, Flint 10, Tin Oxide 6.  Fire to 1260 C.

2.  Potash Feldspar 50, Whiting 20, China Clay 15, Flint 10, Tin Oxide 6.  Fire to 1250 C.

3.  Cornish Stone 40, Ball Clay 10, Whiting 10, Lead Bisilicate 20, Zinc Oxide 10, Titanium Oxide 10.  Fire to 1200 C.

4.  Potash Feldspar 10, Whiting 10, Flint 5, Lead Bisilicate 50, Zinc Oxide 15, Titanium Oxide 10.  Fire to 1100 C.

Mike Bush had been experimenting with painting pure ash on to clay.  He showed us several examples using a variety of oxides underneath the ash.  The results were very similar, and resembled the effects produced in a wood fired kiln.

Diana Carter showed us an interesting dry blue glaze.  Painted on thickly it produced a soft blue.  Thin application resulted in blue with brown breaking through.

Potash Feldspar 35, Whiting 72.5, China Clay 14.25, Bentonite 7.5, Red Iron Oxide 2.5, Cobalt Carbonate 2.5.

The next Glaze Group Meeting will be on Tuesday 9th of May 2006.  Everyone is welcome.  There is lots to learn in a convivial atmosphere.  Bring your experiments, failed and successful; and an American lunch.  Let Diana Carter (01962 777297) know if you plan to attend.