Wednesday, September 12, 2018

Glaze Firing...

It's been a long time since I've done a glaze firing. I did a couple of biscuit firings but that meant that things were really piling up in the workshop and I was pretty much running out of space to even put things down. I needed to get on with it and glaze some things so I could make some room, you know? 

Glazing is not my favourite task. I obviously love the look of nicely glazed ceramics, but it's such a fiddly job, and so prone to going wrong, that I dread it just a little, because the danger of ruining a much-loved item is so very real. 

Take that, and add to it that glazing materials are hazardous and best not used around children, and you've got the perfect playground for some heavy procrastination. ;)    It's taken me months to get to the point where I could shut the heavy kiln door and programme my controller.

That said, once it's done and everything is loaded, it's all very exciting. A kiln firing takes a good 12 hours, and after that it takes another 48 hours or so for the kiln to cool down to ambient so it can be opened safely and without danger of cracking any pottery or glazes due to thermal shock. That's a whole lot of nervous waiting, because you never quite know what you are going to find once you crack that kiln door open - is it all going to  be shattered, or will it have worked?!

This firing was to stoneware,1220 degrees C. I switched the kiln on at around 8am in the morning and because Betty is quite an old kiln I checked on her several times that day to see if she was doing her job. She was, and by the afternoon when I checked once more, there was the tell-tale glow from the air hole at the top where I'd removed the bung to help the kiln breathe. Can you see it? 

Closer look...

The temperature at that point was 1147 degrees and rising.

It's always fascinating to me how the inside of the kiln starts to glow once it gets to the really high temperatures. This is the glow through one of the ceramic bungs in the door, which, by the way, are not normally transparent. 

Betty reached temperature at around 8pm that evening and then started to cool down. It was a loooong wait, because after the initial fairly quick drop in temperature down to around 600 degrees, which she managed overnight, things slowed down and it took a further day and a half to get to around 45 degrees, at which point I couldn't take it anymore and cracked the kiln door open. It was still a little early, and there were a few ominous pings (that's the glaze cracking...), but nothing too dramatic happened, and I don't have anything in there where a few minor cracks in the glaze should matter in the least. 

I forgot to take a shot of the kiln right when it was opened, so in this picture a few items have already been moved. 


Overall it was a  very successful firing, but a few things did go wrong - right on the top shelf I had a big plate that I had glazed in white, with small chips of blue glass to melt in all the little indentations in the plate. That part went well, but apparently I had not taken off enough glaze at the bottom of the plate and the whole thing got stuck to the kiln shelf and, because it couldn't expand and contract the way it needed to during firing, cracked in several places...

Ah well, you win some, you lose some...

On the other hand I had a few things that turned out quite lovely:

I think, overall, I'm pretty pleased with this glaze firing! 

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  1. Such a shame about the plate but what a great success with the other things. I have scrolled up and down a few times and can't decide on my favourite, they are all eye catching in their own way.

  2. Such interesting looking pieces. It is a shame about the plate, the pieces of blue glass are stunning.

    Visiting from bethere2day

  3. I didn't realise that making pottery would be so complicated. You are very clever Iris.

  4. The little house is fun. I can see you putting LED lights in there and using it for a winter scene.

  5. These are incredible works indeed. I love the house and the one with turquoise spots

  6. Interesting works of art!
    Thank you for sharing at