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Firing My New Kiln


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#1 tomhumf

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Posted 07 May 2014 - 01:34 PM

Hi Guys,

 

I'm a newbie to ceramics... We recently bought a kiln from ebay and have just had an electrician hook it up in our garage. Reading most firing schedules, it instructs to prop the lid open for an hour or so at the start to warm the kiln slowly. 

 

The manual I have found online for the kiln is quite general to all their models so it's unclear about starting the firing. It's an  Olympic model S1823, but an older version than is available now, it has a kiln sitter device.

 

On our kiln, there is a padlock type catch that requires the lid to be closed, before the power can be turned on. I'm guessing it must therefore be ok to begin firing with just the 2 peepholes, and the hole in the lid unplugged? 

 

 

Thanks for any input..


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#2 neilestrick

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Posted 07 May 2014 - 01:53 PM

If you have lo-med-hi or numbered (infinite) switches, there's no need to prop the lid. I'd keep the lid hole closed but keep the top peep open. Unless you have a downdraft vent hooked up to it, in which case keep all the holes closed.


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#3 tomhumf

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Posted 07 May 2014 - 02:12 PM

If you have lo-med-hi or numbered (infinite) switches, there's no need to prop the lid. I'd keep the lid hole closed but keep the top peep open. Unless you have a downdraft vent hooked up to it, in which case keep all the holes closed.

 

Thanks for your speedy reply!

 

Yes it has three lo-med-high switches, there is no vent. 

 

From their manual they seem to suggest keeping the lid hole open, unless I'm confusing the terminology, but I guess it wouldn't make too much difference anyway would it? 

 

 

2. Plug all observation holes except the top, which should remain unplugged throughout the

firing to allow a vent for fumes and vapors.


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#4 Pres

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Posted 07 May 2014 - 02:36 PM

My lid is completely removable, as I do not use the hinges. I have two handles on either side of the 3" lid. I usually start a firing with the lid off completely. However, this is not really needed. The only two things you have to worry about are your rate of temp climb, and the vapors the kiln will produce from your ware. The vapors are of three types, the moisture being first to leave from the atmospheric water and the chemical water inherent in the clay. Atmospheric water is water that is in the room or atmosphere. Your pots will not dry further than the air moisture. Chemical water is the water that is part of the clay formula itself bound at molecular levels.

 

One of the other two vapors come from organic materials that burn out from the clay-bacteria, plant materials etc. These are usually gone be 600F. Then the last of the vapors come from chemicals in the clay changing, these will include sulfur products, and others. These usually are gone by 1100F.

 

Rate of climb in temp is usually recommended to be slow up to 1100F. due to the vapors and one final chemical anomaly. Quartz has a physical change(inversion)  from alpha quartz to beta quartz. This change can be problematic for ware if going through the inversion often causing cracking.

 

This information is meant to give you some background as to why to fire slowly up to 1100F, and then allow a faster climb. At the same time it should illustrate that opening the kiln after reaching temp is . . . . disastrous. Above 1100F, and anywhere above 100F.


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#5 tomhumf

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Posted 07 May 2014 - 03:01 PM

My lid is completely removable, as I do not use the hinges. I have two handles on either side of the 3" lid. I usually start a firing with the lid off completely. However, this is not really needed. The only two things you have to worry about are your rate of temp climb, and the vapors the kiln will produce from your ware. The vapors are of three types, the moisture being first to leave from the atmospheric water and the chemical water inherent in the clay. Atmospheric water is water that is in the room or atmosphere. Your pots will not dry further than the air moisture. Chemical water is the water that is part of the clay formula itself bound at molecular levels.

 

One of the other two vapors come from organic materials that burn out from the clay-bacteria, plant materials etc. These are usually gone be 600F. Then the last of the vapors come from chemicals in the clay changing, these will include sulfur products, and others. These usually are gone by 1100F.

 

Rate of climb in temp is usually recommended to be slow up to 1100F. due to the vapors and one final chemical anomaly. Quartz has a physical change(inversion)  from alpha quartz to beta quartz. This change can be problematic for ware if going through the inversion often causing cracking.

 

This information is meant to give you some background as to why to fire slowly up to 1100F, and then allow a faster climb. At the same time it should illustrate that opening the kiln after reaching temp is . . . . disastrous. Above 1100F, and anywhere above 100F.

 

Thanks for your reply, it is very detailed and informative. The kiln is in an outside garage with ventilation holes near it, and the doors will be open so hopefully the vapours will not be a problem, I guess I should be wearing a face mask if in proximity while firing though..

 

I plan to follow a schedule I found to gently raise the temp every hour through turning the dials up gradually so hopefully the rate of climb will be ok. And yes I won't open it until a day later :)

 

I plan to use witness cones to verify the kiln sitter isn't faulty and lead to over fire. I have the cones that don't stand up on their own. Are you mean to stick them to some clay, and let the clay go green before using them or something? 

 

And looking through a peephole to see witness cones, I bought some 'anti UV goggles' will these be adequate eye protection?   Just read the stickies, and it seems I should use a welders mask, found one on ebay with EN 175, filter shade 11 would this be ok?

 

 

Sorry for all the dumb questions...


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#6 Pres

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Posted 08 May 2014 - 07:55 AM

Face mask isn't really needed, but good ventilation helps, or stay out of the kiln area when firing as much as possible. I had a kiln in the classroom for years, and never had a problem, but did most of the bisquefire over night. Begin the firing during the day, and ramp in afternoon after school, stay until over 1100 and then turn it up. Kiln setter would shut it off at 1or2am. No I did not stay, but I could figure the timing to 30 minutes, and made certain everything worked right every firing. So with the back up timer set, and the kiln setter set I could rest reasonably. I also told the janitors and security people exactly what to do in case of an emergency. Fuse boxes were labelled, and plugs were high on the wall for easy access and removal.

 

Your worst gasses are very very small amounts of sulfur dioxide and trioxide. Sulfur trioxide will turn to sulfuric acid when it meets water vapor. Both of these are environmental pollutants, but the kiln firing release very little.


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