A Burning Question
A few days ago someone posted a question into a Facebook group about when it's safe to open a kiln. If you're a potter you've been involved in this discussion at some point in your life and you know that the answers can be as varied as the number of people involved in the discussion. People who watch me work or students who I teach always tell me that I'm a patient person. I always beg to differ, I'm forced to be patient so I must be, but waiting on clay to dry or kilns to cool is hard.
One of my favorite answers came from a potter who opened the kiln around 350 degrees. The argument was that you cook at that temperature in an oven, your pottery is most likely able to handle that temperature. I like that logic since I make a fair amount of cookware.
For people who are not potters or who are new potters, the reason for the question is because bad things can happen to pots that are cooled too quickly. Logic would tell you to wait as long as possible for the pots to cool, that's just smart. Of course it's like telling a 5 year old to sleep in late on Christmas morning. It's probably not happening, especially if we've tested a new glaze or form. Sometimes we have deadlines and we are pushing things to the last minute because the clay wouldn't dry or thunderstorms cut off our electricity or the garden needed to be planted. Whatever the reason, we always want to crack open that kiln and see the treasures inside.
Potter's at what temperature do you open your kilns?
What events in life do you have trouble waiting patiently for?
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One of my favorite answers came from a potter who opened the kiln around 350 degrees. The argument was that you cook at that temperature in an oven, your pottery is most likely able to handle that temperature. I like that logic since I make a fair amount of cookware.
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| Covered Casserole |
For people who are not potters or who are new potters, the reason for the question is because bad things can happen to pots that are cooled too quickly. Logic would tell you to wait as long as possible for the pots to cool, that's just smart. Of course it's like telling a 5 year old to sleep in late on Christmas morning. It's probably not happening, especially if we've tested a new glaze or form. Sometimes we have deadlines and we are pushing things to the last minute because the clay wouldn't dry or thunderstorms cut off our electricity or the garden needed to be planted. Whatever the reason, we always want to crack open that kiln and see the treasures inside.
Potter's at what temperature do you open your kilns?
What events in life do you have trouble waiting patiently for?
Check out the gallery page - Future Relics Gallery by Lori Buff
Follow my blog with Bloglovin
I err on the side of better safe than sorry. I fire with a slow cool down to 1500 degrees. Since I can't hold pots with my hand at 350 I don't open the lid at 350 and never have and haven't had any problems. I fire with one peep out (no enviro vent), so I pull the next peep at 400 or 375, then the last peep at 350. I open the lid one notch at 300 and let the heat slowly drift out, I do have a fan held on the kiln controller during the whole firing so the fan speeds the cooling somewhat. Next I lift the lid 2 notches at 275, then at 250 I open the lid up completely and look in, I usually wait till 200 or less to unload. I don't usually hear the pinging that other's talk about which I think happens when the cold air hits the hot pots, my reasoning is there is much less reason for the pots to crack from the thermal shock. When I unload my pots I set them on wood or cloth rather than a cold surface so they can still dissipate heat easily.and so their bottoms will not be shocked from the cold.
ReplyDeleteWow Linda! That's a lot of steps, of course you most likely don't see any crazing or dunting with that degree of caution.
DeleteWe just fan until lukewarm, then unload.
ReplyDeleteYou know I'm kidding.
Anywhere under 400 we pull bricks, then pots are pulled around 350 or less.
With tiles, I wait longer.
I don't know Meredith, I saw your fan photo. Hehehe.
DeleteOh hell, i dunno :) I peek the morning after a firing and open the top an inch when my hand can go in safely :) Unloading is a couple hours after that!
ReplyDeleteThat's the ticket Gary, if it's not burning you it should be okay. I like it.
DeleteI fire overnight so the kiln to too hot to open in the morning. I usually pull the plug around dinner time and crack it before I go to bed. It's generally cool enough to unload when I get up next morning. I lost an entire load of bells once because I unloaded too soon....lesson learned!
ReplyDeleteSorry about your bells. Their is nothing like a really bad experience to teach us caution.
DeleteI often share my kiln with other potters in my group and we generally wait for it to get below 200c and cool enough to be able to pick the pots up. I think some of the pinging as things cool depends too on the type of glaze.
ReplyDelete