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temp for opening kiln?

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OK this may sound sillly but I would like to know at what temperature do most folks open their kiln??? My L&L says to wait until it is 250 F or below to open. So of course I open as soon as it hits 250 because one more second of waiting is just too much. But I get the feeling others wait for a much lower temp. So what is the consensus?

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For a bisque load, I'll open the top at 130 to 150F.

 

For a glaze load, I'll prop open the top at 120F and open fully when it gets down to 100F. If it's a cool/cold day (my kiln is in the garage), I might wait a bit longer and let it cool some more.

 

I fire an electric kiln. I fire with a vent . . . turned on at start of firing, turned off when unloading. Plugs stay in.

 

At the studio I also use, some have unloaded glaze kilns at higher temperatures . . . to a chorus of "pings" and crazing.

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I've always kept all the ports in and dropped shreds of paper into the kiln. As soon as the paper stops catching on fire I open the ports. Once I can handle the ware with out burning myself I'll open the door and unload it.

 

I should add that I have a fairly high tolerance for pain.

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Every kiln has uniqueness, you can't generalize it or any method about the kiln such as firing method, increasing temperature, etc. Even in same size of the kiln, potentially different for each other.

Usually the kind of clay determines thermal shock strength. Clay consists a lot of free quartz you must be patient for opening the kiln, but for earthenware you no need worry to much. Also the pot in slip casting technique is more stronger then other technique such as throwing or slabbing in thermal shock phenomena.

I usually open the kiln in step by step. First I open the spy hole. Than if fell warms in your hand, I open the door kiln just little bit. Every a half an hour I open just little bit too.

Meganthwaites likes this

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The kiln Gods are with you. Glad to hear there is no disaster. When you use cones, they can be seen with the light from the heat starting at cone 022. <div>If you put them in by the peep holes set them about 1-2 inches in from the edge of the shelf. You can get kiln safety glasses through suppliers. It is a good idea to place them throughout your kiln to see if it is firing evenly.</div><div><br></div><div>During the last week of school, I was firing kilns. I know about how long they take to fire and will go back to the university to check on them. I usually have them timed to go off before I go home, but was firing several at a time and started one later.  I got up and went in about midnight. I am glad I got dressed because when I was there I locked my keys in the office and had to go search for a security guard to open my office up so I could drive home (forgot a cell phone too). When I lived in Montana, I would drive three miles to my studio to check the kilns and make sure they were off as scheduled. UTB is one the grounds of old Fort Brown built during the 1840s and played a key role in the Civil War. There are books on the ghosts that roam the campus. Spooky place (literally) to spend nights firing kilns.</div><div><br></div><div>I fired a strange (new to me) huge gas kiln this semester and stayed through til midnight. There were 28 18x 18 shelves in there and I couldn't see the cones on the bottom at all by the time it was reaching temperature. The kiln log was flawless. I followed it and had a perfectly even firing. The students were happy about that.</div><div><br></div><div>So welcome to the world of pottery. You have passed the initiation.</div><div>Marcia</div><div><br></div>

Getting the oops messages again and I purposely resigned in before posting. I get oops messages when I sign out too. Anyone else having this problem?

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I always open a kiln way before it is legal. I start with the peep bricks and remove blankets definitely. Then I begin a fan on the closed kiln for about an hour. Turn the fan off and crack the lid a little bit holding it open with a piece of broken shelf. The kiln is usually an orange to darker color. In fact if you take a flashlight and peek in the colors will not have settled yet. Then I go away for about an hour - return and put the fan on low for a while. Then I lift the lid about 3 inches and prop it and continue in this fashion until I can lift the lid wth gloves on, but still cannot touch the pots. The lid remains open at least another hour and maybe longer and then I remove the top shelf and place onto boards. Usually it is still so hot that the second shelf is impossible and I have to wait a little longer. Most of the tme I have to do this because I need to pack and price and get to a show. Otherwise it is a huge luxury to simply allow it to shut off and leave it in there for the weekend before starting to take it out. I might add that when I load I put small things on the top shelf on purpose so they won't split when I open the lid too early. Platters and so on go at least three layers down.

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Ok, true confessions time. I sometimes...ok, USUALLY...open the kiln when it is still hot. I take out all the peeps at about 700 then prop the lid up a little bit when it is 400 or so, then open the lid all the way when it's at 300. I figure I can take a dish out of my kitchen oven at more than that, so why not. I have never, never had a problem. Except once I singed my eyebrows peeking but that was at a much higher temp. I am not a patient person.

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Ok, true confessions time. I sometimes...ok, USUALLY...open the kiln when it is still hot. I take out all the peeps at about 700 then prop the lid up a little bit when it is 400 or so, then open the lid all the way when it's at 300. I figure I can take a dish out of my kitchen oven at more than that, so why not. I have never, never had a problem. Except once I singed my eyebrows peeking but that was at a much higher temp. I am not a patient person.

 

 

I've wondered why we can't open an electric kiln and take things out at up to 425 since we take pottery out of an oven at this temp sometimes, but I haven't risked it and usually wait until the temp is around 120.

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Ok, true confessions time. I sometimes...ok, USUALLY...open the kiln when it is still hot. I take out all the peeps at about 700 then prop the lid up a little bit when it is 400 or so, then open the lid all the way when it's at 300. I figure I can take a dish out of my kitchen oven at more than that, so why not. I have never, never had a problem. Except once I singed my eyebrows peeking but that was at a much higher temp. I am not a patient person.

 

 

One of the reasons I schedule an outing after firing a kiln, so that i won't be around to get anxious about opening it. Sometimes I sleep in quite a while, because even though it is electric, it has no kiln setter-all manual baby!

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Oh I love the phrase plug shuffle! What a variety of answers to this question...wonder what that proves, besides the obvious one that the impatience quotient varies among potters. Do those of you who open early get more crazing than if you'd waited?? Of course crazing is pretty, but isn't it bad on the inside of pots that will hold food?

 

I'm a new potter, 72 years young and after taking classes I've now had my own cellar studio for one year. I LOVE making pots! Electric kiln in the garage, and I agonize every time about this kind of question. How about the other end of the firing cycle—is it okay to close the lid and bung holes at the beginning and set it for a fast glaze firing?

And how about the bisque firing. If I'm sure the greenware is fully dry is it okay to do a fast firing, with everything closed??

 

Ginny Clark (Fort Wayne IN)

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Oh I love the phrase plug shuffle! What a variety of answers to this question...wonder what that proves, besides the obvious one that the impatience quotient varies among potters. Do those of you who open early get more crazing than if you'd waited?? Of course crazing is pretty, but isn't it bad on the inside of pots that will hold food?

 

I'm a new potter, 72 years young and after taking classes I've now had my own cellar studio for one year. I LOVE making pots! Electric kiln in the garage, and I agonize every time about this kind of question. How about the other end of the firing cycle—is it okay to close the lid and bung holes at the beginning and set it for a fast glaze firing?

And how about the bisque firing. If I'm sure the greenware is fully dry is it okay to do a fast firing, with everything closed??

 

Ginny Clark (Fort Wayne IN)

 

 

Fast firing a bisque-na na na with a waving finger at the same time! You have all sorts of issues to deal with when firing the bisque. First the clay only gets as dry as the atmosphere so, you water smoke for 2 hrs with the lid cracked or open to drive out the atmospheric moisture. The you fire slowly to around 500F to remove impurities (organic) from the clay-burning them out. then around 1100F the clay goes through quartz inversion, which can cause a lot of cracking in bisque if gone through too quickly-then you can turn up the kiln to high and fast fire! However, by that time most of us have taken at least 6 hrs to get there! Some even more. To do otherwise would mean opening the kiln to a pile of rubble that could have damaged the brick, elements lid and floor-could have, not often though.

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I begin pulling plugs in the high 400's. I take my first look in the glaze kiln at about 350 or 325. I crack it and leave it cracked at 300 and I take stuff out at 212 or even a little higher. I've been doing this twice weekly, for 2 years now and I have no incidents. I'm firing mostly bowls from 10" to 14" across and 3 - 5 inches high.

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The plugs don't matter much. If I bother putting them in at all, I usually pull them when the kiln shuts off, even if I'm doing a controlled cool down. I crack the lid just a little at 500-600 or so depending on the firing and how anxious I am to unload. I usually start pulling pots from the kiln at around 250-300 degrees, especially if I'm cold.

 

Jim

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When I was in school, we were taught we could open the kiln at 400 degrees. Prop it open, that is. Then when it got down to 300 degrees, we could open the lid fully and unload as soon as we could handle the pots without getting burned, or setting the place on fire.

 

Since then I have read a lot about firing my kiln, and I have always been horrified at the sound of the crazing pings, and that is not something I usually am trying to do, so I leave it alone. I pull a plug at 350 or so, but usually let it get down to 150 or so before I prop the lid open a little. When I can touch the lid after that, and it doesn't feel hot, I open it all the way, and can unload then. I (knocking on wood, here) have never had anything break or explode in the kiln- YET, that is-, and I don't look forward to that.

 

I appreciate all the info here. It is a great help to me.

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i am also sometimes one of the impatient potters. i opened the kiln the other night at 11:30 pm so i would be able to sleep. it was at 220 degrees and i have gloves. the problem is that there is no room around the shelves to lift them off safely so i have to be careful to look only at the top shelf and guage the look of the rest of the load from what i put on the top shelf. didn't sleep well since i was able to see right away that all the pots i had done in one of the glazes was too thinly applied. (damn sprayer!, never me)

 

some of you have mentioned "dunting" without realizing that it is a condition caused by poor glaze fit, not firing. dunting can happen weeks after a firing and will startle you with the loud PING!!! i had this problem until i changed the clay body, the glaze recipe and the kiln. dunting is not a good thing. somewhere there is a crack in the pot even if you can't see it. a well made stoneware bowl will ring like a bell if tapped. if it goes clunk, it has a crack.

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This has been interesting. I'm glad to know I'm not the only one who can't wait until Christmas! It depends on what else I have going on. I try to schedule errands the next day so I am not home and cannot open the kiln too soon. I don't like hearing the pings. However, I do tend to peek very quickly at the top shelf when the kiln is dark but still way too hot. I put my hand over the top peephole and if it doesn't burn my hand in 3 seconds, then I can peek. That's it, though, and then wait until it's at least down to 200 before opening all the way and unloading. It looks like there's not one right answer here, but I'm guessing you are best off to wait until it's completely cooled or very close to it.

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OK this may sound sillly but I would like to know at what temperature do most folks open their kiln??? My L&L says to wait until it is 250 F or below to open. So of course I open as soon as it hits 250 because one more second of waiting is just too much. But I get the feeling others wait for a much lower temp. So what is the consensus?

 

I did what most here do, pushing a bit at 300, taking plugs out etc... Then one day at about 250 degrees, I got to the shelf with the porcelain mugs, (the rest of the pieces were stoneware) and they had all shattered from thermal shock. Since then, I leave it until it is room temp.

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There are soooo many things that can go wronge when I do my best. that I'm not going to temp fate by trying something I KNOW can cause trouble. I never hurry the cooling , no plug shuffle, no propped lid, untill it's 200*, then, If I have a pressing reason to get something out, or packed to go to gallery, I will pull out top peep, then prop lid 1 " at 150. Don't every open lid untill under 100* Lots of times I do nothing at all with lid and peeps till under 100*

 

It's not worth it. have seen the results too many times.

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I'll often peek at the top shelf, but usually leave stuff until its cool enough to handle with bare hands. Sometimes I break down and grab the pot holders though, but I really do try to leave stuff in until its cooled to 150deg or so. I don't mess with the plugs but I figure the envirovent will do just as well as anything for venting :)

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I high fire an earthenware clay (slipcasted). I open my top bung at 428F(220C), Front bung open at 392F (200C) and open door at 356F (180C). If I need to inspect a new piece, and I can get to it, I will remove it then.

My friend works with porcelain. she opens her top bung at 572F (300C)

No issues. Food safe , etc. Oh, and my friend can fire her kiln every 24 hours, should she want ... Quick ramp-up and down.

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After my first disaster opening my kiln too soon many many years ago I learned to have a lot of patience. I fire with the top peep open but when the top temperature is reached and the firing is complete I insert the top peep so no bursts of cool air enters the kiln from doors opening and closing.

 

 

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