Tuesday, 19 August 2008

New elements installed

I picked up new elements from Kiln Elements. Stan was very helpful and even made up custom coils for my FX23 that were 7 ohms instead of 8's and 9's. Because my SSR is rated for 50 amp, going to 7 ohms nudges up the amp draw a tad, which should help be reach cone 10 easier (or at least with a margin)
Posted by tim at 2:13 PM in My adventures in throwing clay, slip casting, and firing.

Monday, 17 December 2007

Lesson of the week: One can't rush pottery

So I wanted to get a piece done by monday, and it was Friday. I figured I could throw Friday morning, and candle the piece in my oven friday night, then bring it to 220 in my oven, and bisque fire starting saturday morning, then glaze and glaze fire sunday.

Well, it all went awry quickly. The bowl didn't survive candling. I tried to put 'clay dust' in the crack, thinking it'd bitrify closed, but it didn't end up that way in the end. The bisque fire was fine, the bowl seemed OK, but after glazing, it ended up widening the crack greatly.

The other problem is the glaze is now cratering. Perhaps I need to let the glaze dry more between coats, and certainly let it dry longer before firing. I think there is a bit of water that 'erupts' as it turns to steam, causing these craters. It might also be temperature retention in the kiln, as I've done two 'single fire' cases and the results have been poor. But my first glaze fire with 4-5 pieces turned out nearly perfect.

Getting the kiln controller online will probably help too. It's a pain to babysit the kiln and track it's temp, and fiddling with arcane firing controls.

Posted by tim at 6:09 PM in My adventures in throwing clay, slip casting, and firing.

Wednesday, 28 November 2007

First Glaze Fire

The red cup ended up with kiln wash boogers inside, not sure how that happened, maybe from the shelf above? It's not ruined, but it could have been better The black looking cup and bowl are actually a deep blue. Maybe 2 coats would have been enough, or maybe my kiln got too hot.

The green bowl should have been a patchy teal with brown ridges... instead I just got a nice green. I don't mind it, but I was expecting something quite different.

I also had a chip I painted with Shinubi Ice, but the 'ice' pattern didn't form. At least I know it's transparent now. I'll have to make some small tiles and paint different coats. Maybe the blue should be thinned out more with water? Anyway, I need to test all the glazes

The red cup is an underglaze with clear glaze on top. It looks orange to me in person. It seems like red is actually hard to come by. It might also be 'burnt' by the heat. Again, probably have to test some more.

Sunday, 18 November 2007

Kiln online

Finally, after, uh, 2 years, I finally was able to power up the kiln. First step was the 200 amp upgrade to my house, and 2nd was rewiring the kiln itself to a '4 wire' 220 plug. NEMA 14 I believe it's called.  Anywhoo, the ol' pottery book says to 'candle' the kiln overnight, which means to put it on low overnight to bake off all the moisture.  So far it's been 3-4 hours and there is still steam rolling outta there (the lid is cracked slightly open).  It's been in my garage for quite a while, and I imagine the fire brick is rather porous. It's actually fogged up the windows in the garage.

I also tried my hand at slab work tonight, but I'm not quite sure how to get the rolled clay off the board! Maybe I'm supposed to roll it on plastic and let it dry out a bit. I'm not sure. I'll have to read up on it more. I'm not going to buy a slab roller just for this. In the meantime, I threw a cup on the wheel. It's a bit wonky, but it should be good enough to drink out of. I have glazes as well, so I'm all set to complete my first piece this week.
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