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Accidentally started manual kiln on high not low

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Hello all- I’m new to pottery, been at it for about a year, and got my own kiln a couple months ago! It’s a skutt, no idea what model but it’s made in 1986 I think. Anyways- it’s been working great! 

I started my glaze firing tonight at cone 6- I usually prop the lid for an hour or two on low and close the lid and put peepholes in for another hour, medium for 3 hours and then high till finish.  Well silly me I had the dials at high and not on low accidentally! Went to check on it after an hour and a half and then realized my mistake! 

so I didn’t really know what to do, I figured putting it back on low wouldn’t help and if any damage was done it has already been done.. I switched it to medium and put the lid down. Now will continue the normal firing schedule of 3 hours on medium and then switch to high to finish.


my question is- what would you do in that situation? Would you have just stopped the firing and redo it after it’s cooled? Would cooling it cause more damage to the glazes? Hoping I made the right call and can update tomorrow but was hoping to hear what others would do incase I ever mess up again! 


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As a glaze firing, not much potential water to dry out so I would have done the same as you. Most of my glazes fire fine at 5 hrs, so I might have left it on high actually. I think you made a reasonable choice. If it was a bisque fire I might have been inclined to switch it to low for a bit and get it back on schedule knowing if anything was wet, I might have already damaged those wares.  Bisque firings run about half the speed of glaze to give enough time at temperature to burn out all organics effectively so that is why I potentially would  revert back to slow.

Edited by Bill Kielb
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  • 1 year later...

Hello Daisy. Welcome to the forum.

If you fired your pots to bisque temps, before you glazed them, you shouldn't have a problem. I fire my cone 6 slip cast porcelain on High, from start to finish, with no problem. (with a cone 06 bisque beforehand.) The elements lasted 25 years so I saw no ill effect.

Definitely do not want the pots to cool to room temperature. Re-firing a partially melted glaze can sometimes create terrible results.

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as new to kiln ownership, there are a number of things you should learn to watch for.

first is that whenever the kiln has fired, the sitter turns it off but does not reset the dial to low.  it remains on high until you change it.   remember that.  form the habit of changing the dials to off before you open the kiln.  

the dials indicate the stage of firing you are in so you can turn them up gradually.   if you have a kitchen timer, set it for one hour when you start your kiln.  if your kiln has sections and/or more than one heat dial, start the kiln with the bottom dial on low.  use one hour on timer to then add the next dial upward to low.  set timer for one hour.  when you reach the last dial nearest the top, do the same, one more hour on low.

once you reach the last dial, start again at the bottom dial and turn it to medium.  set timer and repeat the steps you followed on the first trip upwards.  repeat for high.

if you are concerned with water steaming out in a bisque firing, hold a piece of glass or mirror just above the top vent hole and see if there is fog on the glass.  i use the glass when the bottom dial goes to high.  steam will stop coming out usually just around that stage, temp about 900 to 1100.  this depends on the dampness of the greenware you have in the kiln.   your turning up the heat gradually will probably have allowed the moisture to evaporate safely.  if you stick WET greenware into the kiln,  all bets are off.  that is a bad thing to do, do not do it.  dry your greenware.  it is not fun to clean out a kiln full of damaged bisque and vacuum up each little particle from the element grooves.  lots of work because you were not thinking.

though i have never experienced a successful glaze firing as soon as 5 hours after starting the kiln,   mr kielb has said many times that he has.   glaze firing does not involve wet clay unless you have  just now dipped a piece of bisque in very watery glaze and stuck it in the kiln immediately.   that may cause the piece to blow up from the water in the ware.  that will mean that the pieces in the kiln may be damaged beyond repair.  even things on different shelves.  i do not see any benefit in firing fast.

you might look at some books about electric firing,  jeff zamek has one with about that title.   do not dismiss info in older books.   they were written when your kiln was new technology.

my first kiln was new in 1972 and i was absolutely dancing with joy when i got it.   the shop where i bought it had several kiln disaster samples on the walls.   one was a  pile of white clay stuck to the kiln bottom, about a foot high.   that person had not understood cone numbering,   cone 06  is NOT the same as cone 6!  i sold that kiln in 1990 to a lady who also danced.









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