neilestrick
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Posts posted by neilestrick
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Start reduction somewhere around cone 012-08. Your wife can fill you in on cones if you're not familiar with them. I wouldn't waste much time on automating it, because adjustments to the burners are almost always paired with an adjustment to the damper. And every firing is a little different, so adjusting according to what you see happening is very important. You'd need a lot of different sensors to effectively automate a gas kiln.
If any of the fiber behind the bricks is exposed where the bricks are broken, I would cover it with new bricks since it may not be rated for high temps.
Most people use a kiln shelf as a damper. Google search should turn up some examples.
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Lots of little patches or something on the bricks when you zoom in.
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Welcome to the forum!
Unfortunately, the chimney isn't going to work. It may be the correct size, but the heat is going to destroy it in no time, and it'll likely be glowing orange outside the kiln. You also need a damper in it, and because you're using venturi burners it's probably far too short to provide the secondary air needed for combustion. I highly recommend looking at a kiln design book like Frederick Olsen's 'The Kiln Book'. It's a somewhat outdated but it's got some solid design work in it and it's really about the best we have. It'll give you the calculations needed for flue opening dimensions and chimney height. Your chimney needs to be built from firebrick to at least the height of the kiln, and then you could transition to metal after that if needed, but it's often easier to just keep with brick.
Where will the kiln be located while firing?
What is the BTU rating of your burners?
How thick are the walls, and what type of insulation is behind the bricks?
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Kilns 7 cubic feet and smaller will need a 60 amp breaker at most, with an actual draw of 48 amps at most. 10 cubic foot kilns, if you want it rated to cone 10 (which you do if you're glaze firing to cone 5/6) will need an 80 amp breaker, with an actual draw of 63 amps. That's a really big kiln for most home studios, though. 100 amp service will be great, and leave you plenty of power for running lights, wheels, etc. Kiln vents run on a typical 120 volt household circuit. The only thing that may max out the system is heating, depending on how that's done. Depending on the layout, you may not need to run the heat while the kiln is on.
- Bill Kielb and Hulk
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It may dry and pop loose. If it's too stuck it will crack as it dries and shrinks but there's nothing much you can do about that now. Worth a try just letting it dry. Once it's firm enough you may be able to peel off the styrofoam. In the future, lay a piece of newspaper or paper towel between the clay and tray, or dust the clay with corn starch before putting it on the tray.
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@Paulo316 For low fire clay to work it'll have to have a glaze that fits perfectly and doesn't craze. That will take some testing. Is she using commercial glazes or mixing her own?
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I use 3 versions of the same clear- one clear, one tinted light blue, one tinted light yellow. I do all my decorating with underglazes so that's all I need. I tell my students with home studios to find 3 glaze combos that they really like- each combo may be two or more layered glazes (or even single glazes if that's your style)- just 3 combos that they like and that kind of go together in style, and then use them over and over and perfect applying them so they can be really successful with every glaze load. 3 options will be plenty to offer to people when you start selling, and will be manageable for keeping different forms in stock in all 3 combos. It may take 6, 7, or 8 separate glaze to create all 3 combos, and that's manageable. Trying to maintain a dozen glazes in a home studio can get pretty crowded. Once you've perfect those 3, you can start testing other combos so that you can retire combos every few years and keep your offerings fresh.
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Which program are you using? If you're doing a Cone Fire program, try a custom program or vice versa and see if that works. What exactly does it do when you press start- do relays click? It reads 'Idle', not complete or something else?
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9 minutes ago, Paulo316 said:
My guess is that my finished bottle is too porous and that I need a different / stronger glaze?
Welcome to the forum! This sounds mostly accurate to me. The issue is more than the glaze, though. If you have a porous clay body then the glaze must fit perfectly. Any crazing (crackles) in the glaze will allow the liquid to seep into the walls of the porous pot, where it can grow mold, as well as just evaporate the liquid. While you can find a glaze that fits well, the better solution is to find a clay body that will vitrify and a glaze that fits it well. You won't have any weeping issues that way. What temperature are you firing to, and what type of clay are you using?
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Even if the materials aren't rated high enough, they shouldn't change the insulation factor all that much until they've really shrunk up. If you're getting gaps, then that could definitely be a problem, though. Only the hot face would be an issue, not anything above it. Looks like you could put another layer or two of blanket on the top.
Have you checked to make sure the burners didn't get some crud in them during the rebuild?
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I would just leave the stuff on there and put it up under the kiln. It's really just there to hold the gasket in place while placing the cup. Once it's in place the gasket won't move. The heat of the kiln will likely dry it out over time, but even if it doesn't it shouldn't affect anything.
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I would not use it for a direct vent for the kiln. It's likely much too powerful for that. For a hood it could work very well, though. The fans used on Vent-A-Kiln hoods are 250-500CFM.
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Think of cones and heatwork like cooking a roast. You can cook it at 350F for an hour, or you can cook it at 275F for 4 hours. Both get the roast cooked through, but the slower cooking tastes better.
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@cspindler How was the original ceiling constructed?
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5 hours ago, elenab said:
If I fire fast with a witness cone 6, would my wares warp and glaze bubble?
Cones react to heatwork, which is temperature over time. But just because the cone melted doesn't meat your glaze will be happy, because firing too fast can cause problems. When glazes melt, they bubble up and then settle down and smooth over. If you're firing too fast they may not have time to smooth over, and they end up cooling with bubbles. You can also get bubbles from over- firing, however in my experience glazes are more likely to simply run when over-fired, unless it's an unstable glaze to start with, or two layered glazes that don't agree with each other. Warping can be caused by over-firing, but it could be related to the construction of the piece, thickness issues, etc.
Witness cones are the most accurate method of measuring heatwork, so trust what the witness cones say. The reason we use 3 is so we can see just how under- or over-fired it is. Was it a half cone or a full cone too hot? Having the next cone will help us answer that.
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Glue will burn off. You can glue it on and then glaze it, and the glaze will fuse it in place, but only if it's a small piece and it will sit in place without any glue. If it won't wit in place then once the glue burns off and the glaze melts the piece will just fall off. It has to be able to stay put with just gravity.
- MeowMixMuncher and Rae Reich
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7 hours ago, elenab said:
But why would the kiln sitter allow overfiring?
If the sitter isn't calibrated properly or the sitter rod is bent then it could over fire. It really shouldn't be more than 1 cone at the most, though. If you're loading the cone wrong that could also cause problems.
I would try the pyrometer with witness cones and see how it goes. Leave the kiln on medium as long as possible, like until the rate of climb drops below 50C/hr, before turning it on high.
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@Arimajol That vent should have come with an angled bracket for the motor that you can use to mount it. Also, the bracket should have feet so it won't rattle if you do set it on the floor.
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Yes, just set it on the floor and it'll work fine as long as your vent duct doesn't have any holes in it. Inspect it a couple times a year. There's nothing difficult about this, just tape your duct joints and use hose clamps and it'll work just fine. It's designed to be simple.
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I believe the RCD is essentially the same as a GFCI, and kilns will trip those. They are not recommended for use with kilns.
Kiln firing times
in Equipment Use and Repair
Posted
@Tammyt What model kiln is it, and which firing program did you use?
In general, not all kilns can keep up with all programs. The controller will allow the firing to lag behind the program as long as it doesn't get too far behind.