Bad times - have I damaged my kiln?

[ShinySnail]

Soooo maybe I should have thought this through beforehand, but for tonight's jewellery class I needed about 20 fimo beads to use in a project and hadnt managed to get round my dads during the week to use his oven so though hey I'll use the kiln...

I programmed it to heat up to 130 degrees at full speed then hold for 20 minutes - but after a couple of minutes I could smell burning and realised that the kiln was on about 250 degrees!
Oh dear, I really don't know what happened - I didn't programme it wrong but maybe kilns are not meant to be used for such low temperatures, or maybe full speed was a bit too much oomph 

Now I have black burn marks on the inside walls, and I'm sure I read somewhere that it can be potentially devastating to a kiln to be damaged in this way. I had a little google last night but couldn't really see much on the subject, but today I'm going to fire it up empty and see if I can burn some of it off.

Does anybody have any knowledge or experience of something like this?
So sad, literally a few minutes of carelessless could have cost me dearly!


Thanks,
Anna

[MadelineBunyan]

I don't know about any permanent damage to your kiln, but I would say that yes, full is definitely too much oomph.

even heating mine to annealing temp I heat at 600 degrees/hr or so, so that it doesn't overshoot.

[sarah t]

i dont really know but maybe you should try a man who does ........

what kiln is it ?

[awrylemming]

I did something similar when I first got my kiln and thought I'd completely ruined it    I fired it empty and it removed the marks completely, although it stank like the devil.  Fingers crossed  

[ShinySnail]

It's an SC2...
Thanks for the info, whoops!
Will try firing it up tonight, what a plonker rodney

[Lee - Kilncare]

Hi matey, panic not. I THINK YOUR KILN WILL BE JUST FINE.

Kilns don't really like running down at those temperatures. They are designed to be working much hotter when losses through the insulation etc come into play, so making it a slower, more manageable unit rather than the wild teenager they tend to be at low temperatures.

When the kiln is down at low temperatures there are a couple of things that screw it up.
Firstly, the kiln is in it's fastest zone between say 150 and 300c or so. Kilns are like ships. Tell them to stop and it isnt instant. They build momentum as the element is much hotter that the air temperature and even when you turn it off, that latent heat off the element continues to heat the kiln. This is exaggerated in a kiln like the SC2 where the element is embedded in insulation as the core temperature of the element is a lot lot hotter than the heat that comes out of the insulation so it continues to push out heat long after it is turned off in this situation.

Secondly, the insulation is still working at top rate and has not started to become saturated and leak heat as it does as it gets hotter.

All in all, if you are firing to a temperature that is low then always program in a ramp speed, say 160c in an hour so that the controller is doing it's best to hold on to the kiln. The slower the better.

The upshot on your kiln....fire it up to 600c or maybe a bit higher, let it cool then take a look at your nice shiny white kiln chamber.
Smoke residue and the likes tend to start to clear at 500c as a good rule of thumb.

[julieHB]

I suppose the white vent stopper should be removed before firing the kiln, so that the fumes get out and away? 

[Lee - Kilncare]

Defo

[Margram]

Also fimo fumes are noxious, so ventilate the room well

[ShinySnail]

Thanks very much for the reassurance - everything was fine (and smelly!)
The whole momentum thing totally makes sense, I hate that feeling of panic!

I shall be more carefull in the future, my fimo beads were orrible anyway... I got to make my tiara with crystal flowers instead 

Thanks again,
Anna x

[Redhotsal]

A "Friend"   of mine persuaded me to fire some PMC which she'd painted on a large piece of (she said) drift wood. The idea is that the wood burns away leaving the PMC as a hollow shell in the form of the wood. It was a large piece so we used my large pottery kiln.

It wasn't drift wood, it was flipping bog wood - harder than ebony - and the smell and smoke....you wouldn't believe! It didn't stop smoking for probably an hour and the kiln was black inside. The smell in my studio was like a kipperer's jockstrap for about three months. The kiln was fine - like Lee says as soon as you can get it up to a decent temperature the black carbon just disappears.

I had to Fabreze my roller blinds several times though.....

[awrylemming]

Oh Yuck ... a kipperers jockstrap?  Sally, that is truly gross    Wot a pong, eh?

[Ian Pearson]

"a kipperers jockstrap? "

Blimey, how does anyone know what they smell like???

Ian

[Redhotsal]

um...er......it's just artistic licence - I haven't been putting my nose somewhere where I shoudln't have.....

[kerensky]

Kipperers Jockstrap -LOL at this - you nutter....