Sunday, May 31, 2009

Kiln update

I'm slowly starting to change gears, leaving projects in the house behind. To be finished after the firing. I'm always slow to change gears like this. I started today with a little kiln work. The kiln shelves are still propped up against the kiln, uncleaned. Today was a beautiful day, so it seemed like as good a time as any to start getting the kiln ready for the next firing.
I thought I might also take this opportunity to share how the kiln has fared its first two firings. For the most part I'm quite thrilled. The side walls of the second and third chamber don't seem to have moved at all, the stucco is holding steady, we still need some more bagwall adjusting, but the kiln has been very responsive during the firings. Of course this is the first kiln Christy and I can really call our own, so I imagine even if the kiln looked like it was liable to fall over in a year or two we would be pleased just to own our own kiln.
I'm particularly pleased with our dampers:

I had never worked with dampers on pulleys before, and I have to say I really like them. Also as a bonus, the 1/4" steel has not warped at all. I had used 1/2" steel in kilns in NC, and I wasn't sure if the dampers would warp being so thin. They were half the price though, so we gave it a shot. It seems like a good choice so far.
The second iteration of the stoke hole plugs are also doing great. I think that the first time around they simply were too fine grained. This time, they didn't warp at all during drying, so they fit quite nicely, and seemed to stay snug, and draft free. I'm pretty pleased with that.

And just as nice is that they didn't show any signs of cracking due to thermal shock like the first ones did.

That leaves us with the 'not so good' news:
When we got our bricks we took everything we pulled off of the old kilns. We then sorted it out into near perfect bricks, decent bricks, so on and so forth. We put all the best bricks in the first chamber, the next best in the second chamber, on back, putting the real junkers in the chimney. Unfortunately it looks like some of the bricks in the third chamber might have been better off in the chimney. As you can see they are starting to foam up around the firebox. Not a huge deal though. After another couple of firings we'll grind/chisel them out as best we can. Maybe ram some castable in there if they need it.
The most perplexing problem though is the first chamber entrance. The arch is notched in around the entrance which we thought would keep the entrance arch from moving during the firing. It hasn't really worked though. Quite a good size gap opens up during the firings. I don't think it's leaking much air, but it looks kind of bad while you are firing. Unfortunately though we made the mistake of filling the gap in after we finished firing the first chamber and were moving onto the second chamber. Of course filling this gap stopped everything from shrinking back down to where it was before the firing started...
It's not that easy to see from the picture, as most of the fill is still in there. You can see on the gap on the right hand side of the entrance though. I'm not quite sure what to do about this one...
The chamber arch is still sitting firmly on the door arch though, so it's not a major issue in the immediate future. It certainly seems like it could become an issue over the years though. Obviously I'll refrain in the future from cramming the gap full of clay and sand. Maybe if it looks like it's leaking air during the firing I can try and seal it up with newspaper dipped in slip. We'll see, as always I'm open to suggestions.

1 comment:

Docks-Pottery said...

Ciao,only a few days we have a blog of pottery. I live in Turin and my name is Filippo Di Giovanni, with my friend Raffaella, three years ago we have opened a studio were we work with ceramica.We have not yet shown around our creations.

I would be pleased your comments on our works. thanks