Finished Pieces and The Creative Roller Coaster

I couldn't sleep at all last night; my head was buzzing with new and exciting ideas. I was almost tempted to get up and start working on them straight away!

I left home to collect my fired pieces tonight in a good mood. I had a few questions to ask the tutor as well. I was interested to know why some ceramic pieces crack in cold weather and some don't - apparently it's to do with the moisture content in the piece, so the problem can be solved by using stoneware (which is water tight even without glaze) rather than earthenware (which is quite porous), and firing at a reasonably high temperature. (Please correct me if I've got a little bit muddled - my tutor doesn't always explain things very well)

I was also interested to know why he fires specifically at 1220c every time, when there is a range of temperatures suitable for the clay and glazes. He said that he had found 1220 was the optimum temperature for the glazes that we use at class. I beg to differ, seeing as I have used the cream glaze twice now (on my little head and also on the "Yes I Can" mug) and both times it has left a bubbled surface. So I have a "Yes I Can" mug with a finish that says "No I Can't". *Rolls her eyes*


He said he buys a clear glaze and adds other ingredients for the colours. The top firing range for the clear glaze is 1220. Common sense tells me that one should fire slightly lower than the top temperature to allow for temperature variations in the kiln, and I also know that adding other ingredients can alter the temperature at which a glaze vitrifies.

Talking of temperature variations in the kiln, this plate and mug were fired in the hottest part of the kiln, and the lovely brown colour that I was expecting has turned into this awful green, which proves my point about not firing at the maximum temperature really. (I'm not sure if the colour shows very well in the photo, but trust me, it's awful) I'm sure he wouldn't do anything as stupid as that with his own pieces.




The plate had warped really badly. The tutor said it could be my clay, as I don't know what the firing temperature for it is, or because the plate needed to be thicker. Oh well, it's a learning curve. How do other people make thin plates without them warping?


I've been looking at other glazes recently and asked my tutor if I could use my own, but he said he wouldn't fire the pieces because it's "too risky". Personally, I don't see what the risk is - if the temperature is within the firing range then what's the problem? And we've already proved that glaze run issues can be overcome.

So once again I feel like my progress is being hindered. It is so frustrating. I just want to learn and progress and improve.

The only pieces I was reasonably happy with tonight were the ones I had least expectation of - my roasting dishes. The small one (light green - achieved by using white glaze first and then green) is a bit patchy, but like I said, I had some trouble glazing it - the glaze was rubbing off in other areas when I was trying to clean the bottom. At least I can have some toad in the hole now!



These have warped slightly in the middle too. I'm guessing that it's because of the quality of the clay at class?

Has anyone else had problems with glazes bubbling? Is it because of the temperature? Actually, has anyone else had these problems with tutors?