Bowls, glazes, a moth, and firing

Well, another firing packed and under way as I write this. Probably a 12.30 to 1am finish tonight, which is getting earlier.... but not as early as I would like. I had hoped to have got my firing away sooner today to make for an earlier finish, but ran into real frustrations whilst loading the kiln. All I needed was for the kiln to be half an inch taller and it would have been all right, but as it was I ended up spending about an extra hour trying to find ways of fitting 8 pots into the kiln, and only fitting 6. So I am late again!

Anyway, I had a mixed bag of bowls from the firing before. Two of my larger bowls came out very differently than planned. Probably I made the glaze just slightly thin and maybe fired a nudge lower than was best for them, but the bowls had a cover of dense crystals without the gaps in between that I had hoped for. I was a bit discouraged to begin with, but have ended up liking one of them.

Crystal glazed bowl, approximately 11 inches diameter.

The other will be re fired with another crystal glaze on top, and may turn out really interesting (I hope!).

I am pleased with a glaze test that I did, in that it has come out as expected, with blue and grey crystals on a iron orange background.


It is rather reminiscent of brush strokes of an oil painting close to, and I think it will look good on one of the larger pots.

One small bowl is rather lovely.

Crystal glazed bowl, approximately 6.5 inches in diameter.

I used it to test the copper green crystal glaze that I mentioned having problems with on my "Two in the morning and all that" post. The glaze had previously shown a rather more alkaline blue green and less crystals than I had expected.

Close up of the green bowl.

This time round, by firing at a lower temperature, I achieved much better numbers of crystals, and the glaze worked well on a bowl. I am fairly sure that the more alkaline colour was caused by using a different bag of feldspar (probably New Zealand feldspar), that a friend had passed on to me. NZ feldspar, I think, is higher in Soda than a regular potash feldspar, and that would account for the colour change and different behaviour.

This glaze by Lasse Östman (recipe #6713/kaeg1) yielded beautiful blue crystals with an almost black background on this bowl.

Crystal glazed bowl approximately 7 inches diameter.

I am very thankful for the helpful start that his website gave me with crystal glazes. I am still using his 6713 base, but am usually making my own additions to it with other oxides and a very different firing regime.

Starting with one base, and then modifying it seems a really good way to learn.

Another close up of the glaze test with the orange background and blue grey crystals.

When I was having the odd glaze behaviour and alkaline colour response, I did try some elimination tests to narrow down the likely cause of the problem. One test that I did was trying the base recipe minus the lithium carbonate that is normally in it, and also trying it with half the usual lithium carbonate. This did not change the glaze colour (I thought that it might), but yielded an interesting stony semi matt glaze with an attractive smooth pebble feel, and also a glaze with lots of dense, small crystals in it. This confirms for me the role that the lithium plays in this glaze as a flux, and gives me more tools to play with if I wish to modify the maturing temperature of the glaze. I also rather liked the glaze without the lithium, and may find a use for it in the future.

This was another successful bowl from the firing (Thanks Lasse!).

Crystal glazed bowl, approximately 10.5 inches diameter.

Its colouring was rather hard to photograph, there is some real complexity in the graduated light background to the blue crystals that my camera seems unable to cope with.

As you can imagine, I have been rather wondering around in a state of tiredness with my head all full of firing and glazing, but I did see this lovely little moth last night.


Sorry I shook a bit whilst taking the photo, the light was appalling. The moth had the most intricate lace like patterning in black and white.