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Hello! New kiln user here.  I have a manual Olympic 1818H kiln with a Skutt kiln sitter LT-3K. 

The instruction manual is terribly vague as far as what the times should be for firing so I don't know what to set the timer for. I followed the instructions but the kiln sitter failed and my pyro bar melted all over the kiln sitter and ruined it.

My question is how do I set the kiln it for a) bisque firing to cone 05 and b) glaze firing to cone5? 

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Hi Spotty!

The targets (e.g. cone 05  bisque, cone 5 glaze) are a combination of time and temperature; it's not just time, not just temperature. My best advice* would be to set cone packs where they can be seen via the kiln's peep holes**.

Consider the timer as a fail safe - set it plus thirty minutes or so over how long it typically takes to reach target (yep, experience necessary). Time may vary due to aging elements, ambient temps, how the kiln is loaded, etc.

Consider the sitter as a fail safe as well (hopefully you'll be able to repair the damage...). Monitor the kiln carefully! Perhaps the more experienced kiln operators leave their kilns alone - I watch/monitor mine very closely... 

I've met several auto kiln users who set and walk away, however, all manual kiln users I know of monitor closely - at least at the end.

 

*I've only three bisque and two glaze firings under my belt, so far.

** be sure to wear appropriate kiln glasses!! I use a pyrometer as well, which provides feedback... Your cone packs (three cones - the target, one above, one below target, hence, for cone 6, a 5, 6, and 7 cone) should be visible. I like the idea of painting an iron oxide line on the target cone - easier to see. 

 

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The sitter should be set to about 1/2 hour longer than you expect the firing to take. It's just a countdown timer- it doesn't control how long the firing takes. When it reaches zero it turns off the kiln. If your sitter bar melted, then it got stuck. You may need to replace the sitter tube if the bar is melted all over it.

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Crank the timer all the way to 20 hours, then check your kiln every hour, and once it gets into the yellow range, check every half hour.  Once the guard cone starts to drop, take note of the amount of time it took, then when the target cone drops, look at your clock again.  The next time you fire, put your timer to a half hour past the target cone time and bobs your uncle.

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spotty, there really is no simple answer to your question other than liam's sensible suggestion.

every person makes pots that are individual to that person.  putting them in the kiln and then thinking they should fire in the same amount of time as the nearest other potter just won't work.  maybe you make very thick, heavy pots and get 4 of them into the kiln.    maybe that other guy puts 50 tiny things in the same kiln.  maybe you use 1 shelf and he uses 5.  

try liam's suggestion.   personally, i have had the timer shut off the kiln before it was fired because i forgot to set it.   it all depends.

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Unfortunately, you have to do a firing to figure out how long to set the timer. Get some large self supporting cones that you can see through the peep holes to avoid another over-firing, and so you can make sure the sitter is calibrated. You'll want cones for the cone you're firing to, and the cones one higher and lower. So if you're firing to 04, get 03, 04, and 05. If you're glaze firing to a higher cone than your bisque, you'll need to do another test for the timer for that.

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Did you adjust your kiln sitter when you got your kiln in place?   Did you make sure the kiln was level?  You probably  didn't ruin the kiln sitter just the bars that holds the cones,  they are easily replaced and are inexpensive.   You can find some color charts on the internet that can give you a idea where the temp of your firing is at by the color.   I just replaced the porcelain cone assembly in the sitter,  it was loose feeling and I was having to adjust the sitter a lot.   It is just part of maintaining a kiln,  I have replaced the assembly and the lid on my Skutt  three times in the last 35 years.  It depends on how much you fire and what temps you fire to on how long your elements last.  I have three kilns, my big Skutt isn't heavily used.   Maybe on your next firing you could get someone to help that is familiar with firing electric kilns.  Denice

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Thanks for all the suggestions!!  The new tube assembly just came in today.  (The cone melted and fused the cone supports, sending rod, and tube altogether.  :( ) Soon I will try firing again.

This was what I gathered from the kiln manual for a 05 bisque firing...

  • wedge lid open, fire on low for 10-12 hours
  • fire on medium for 1 hour
  • remove wedge and fire on high till shut off. 

Does that sound like a good plan?  If I set the timer to 20 hours as liambesaw suggested and check it, think I will be in good shape?  (Well, as good as shape as I can be :D )

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If I had a manual kiln I would follow Hulks advice and add a pyrometer so I could watch whats going on in the kiln temp wise and add a cone pack he mentioned with one cone below, one cone dead on and one a cone number above the target. The thing is the time changes as the elements wear out and since the kiln is manual you have to make the ongoing adjustments or I guess just wait until a load gets under-fired. 

Amazon has some thermocouple type ones and I saw one at Sheffield.

https://www.sheffield-pottery.com/Paragon-Kilns-DT2-7-Digital-Handheld-PYROMETER-p/pdt27.htm?_vsrefdom=adwords&gclid=Cj0KCQjwocPnBRDFARIsAJJcf94YqOp_8-vCHkflwMR0It2bS4a6BHV2qhyUTRoueHuU7BDLr46u2QYaAqXQEALw_wcB

 

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wait, wait, wait, spotty.   how many switches are on your kiln?  i looked at olympic's website and there is no model with just 1818H that i could find.   is there a way to see a photo of the kiln itself?

firing on low for 10 to 12 hours sounds extreme.   if your work is thoroughly dry, there is no need to fire on low for that amount of time.   and "wedge" could be half an inch to 6 inches or more.  maybe there are other kiln manuals that are more clear.   have you tried calling them to ask this question?

Neil, what do you think?

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On 5/30/2019 at 7:21 PM, liambesaw said:

Crank the timer all the way to 20 hours, then check your kiln every hour, and once it gets into the yellow range, check every half hour.  Once the guard cone starts to drop, take note of the amount of time it took, then when the target cone drops, look at your clock again.  The next time you fire, put your timer to a half hour past the target cone time and bobs your uncle.

Thank you! I'm going to do this for my bisque firing,  but what timer amount do you suggest for a glaze firing?

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If you need to make sure things are dry, or if you have thick pieces, then put just the bottom switch on low for a few hours or overnight. Then go all switches on low for 1 hour, then medium for 1 hour, then high until done. No need to prop the lid once you go all on low. Just keep the top peep hole open if you don't have a downdraft vent. If you do have a downdraft vent, then keep the lid closed and all peepholes closed for the entire process with the vent on.

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Hi Spotty!

fwiw, my bisque firings take longer than glaze firings; even though the target temp is lower, I'm slowing down the rate of temperature increase in the ranges specified by regular contributor Glazenerd, see links in second post, here

 

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