Firing ceramics with an electric kiln.

[Pat]

Anyone familiar with firing ceramics in a kiln? A friend of my wife gave her an electric kiln and a bunch of molds. It is about the size of a small porta-potty and is 240 volt. I know they get hot and stay hot for a while but have no personal experience with how hot the outside gets or how extensive the fireproofing around them needs to be to not endanger the house and so on.

I told her I would make a place for it in the new house in a corner of HER PROJECT/TEA ROOM. I envision a small fan and a vent to the outside to dump the heat outside in summer or at least an operable window in its little "closet". If there aren't noxious fumes (at least in some of the stages requiring heat) I could arrange it so the heat stayed inside the room to help recover the heat in winter. Open the window when running the kiln in summer and close the window and open the door when you want heat in the room. I haven't read but will read the mfg data plate and see how many amps or watts it wastes, uhh err ahh, I mean uses.

I'm open to suggestions on how to locate this thing for safety, ease of use, and if applicable, energy efficiency (assumes that sometimes it won't generate foul smelling or toxic fumes but I don't actually know about that)

Pat

[WVBill]

Pat: My wife has a small electric kiln and I set it up with pretty much the same attention I would give
to something like a keorsene space heater although I think that may be overkill, actually.
My experience has been that it's pretty darn well insulated.
As I recall, I could put my hand within 5 inches of it while it's operating. So I don't think you need to worry too much about venting out excess heat in summer or hoping to use it for heat gain in Winter.
There's a reason and a benefit to it being so well insulated that it takes a long time to heat up and cool down.
If you know the manufacturer you might want to contact them for their "operator's manual" that I'm sure will give you specifics on
operating location safety.

Although I've never smelled anything while it's operating, I would guess that some of the underglazes, glazes and paints
can emit fumes while being "cooked" - you might want to read the labels there to see if they have any warnings.

My wife's unit stands about 28" tall and 18" in diameter. It's a 110V unit but requires a 30 amp circuit. In spite
of this, it seems to be pretty energy efficient and I've not noticed big spikes in electric usage when she operates
it. In fact, I've gone out and looked at the electric meter and it doesn't spin all that fast.

Best of luck with the ceramics.

By the way, the process of cleaning the greenware will generate fair quantities of very fine ceramic dust.
Just be aware of this when setting up her project/tea room. Our experience was that we had to have an area
set aside for ceramics only or the dust would get all over the other ongoing projects on the table.

[TimSullivan]

I can only tell you that in the schools were I worked they could only be run at night when no students were around. They were in an enclosed room and there was a serious vent to the outside. If I remember correctly it was a 500 cfm fan. Some of the glazes can be a problem so check everything out carefully.

[Pat]

WVBill & tenebrous, Thanks guys. I sure don't want any unhealthy or unpleasant outgassing to contaminate our IAQ (Indoor Air Quality) via our HVAC (Heating Ventilation and Air Conditioning) system. I was at Lowes today after reading your posts and in their power tools section I saw a $299 dollar air filter for shop use, Delta Brand. As it was the last one and they had it marked down and I had just received your cautions I was INTERESTED. Apparently they weren't hot movers since it was deeply discounted. It was priced at $139 so I bought it. If it helps my wifes situation it is money well spent, if not, I'll use it to help control dust in the new shop I will be building closer to our new house. This isn't one of those things with a vacuum cleaner bag that is plumbed into a dust collection system with pipes going to dust producing tools. This can be mounted overhead or on a bench or on a cart to wheel around to use where you need it. It is essentially a fan in a steel box with a big reuseable "roughing" filter in it and a "throw away" final filter along with some timer circuits to allow setting it to run for a specific number of hours and a hand held IR remote for the truly lazy,dust fighter. Supposed to be good for sanding dust and such and for more "dust free" finishes. Oh well, maybe P.T. Barnum was right.

Ceramic dust from working with green ware... I haven't served my apprenticeship yet so am jargon poor. I think I know green ware isn't glazed yet and if you are making dust preparing it I suppose you are cleaning off mold marks and like that. I guess this would be before any firing???? HMMMM, maybe I'll need to come up with a way to control the ceramic dust as I know that sort of dust can't be good to breathe. Back in the days when I was the Quality Engineer for a company that made flying disk memories (Digital Development Inc.) we had flow booths with big HEPA filters so the techs could work in class 100 clean room conditions (fewer than 100 particles per liter of air that were greater than 0.1 microns in diameter. I designed/redesigned some of their flow booths to markedly improve performance. It should not be difficult to set up a workbench that is sort of a clean workstation in reverse, where instead of "extruding" a 4x6 ft rectangle of clean air at a minimum rate of 125 Ft/sec across the top of the workbench, you run the air across the bench into the filter and recirculate the filtered air. We ground ceramic/ferrite pole pieces for the read/write heads but used a water slurry so dust was under control. Surely ceramic dust isn't any worse than silica dust and is probably less a menace than quartz fibers from working quartz (like glass blowing).

Since she is also interested in trying her hand at stained glass the wind drift across the workbench into a filter might help control glass "dust". There are lots of itsy bitsy pieces of glass that sort of spray out from a glass cutting/breaking operation that I wold rather not have propagated around the house.

Thanks again for the heads up, It was a timely intervention, considering the air filter I got on discount.

Pat

[WVBill]

Pat: You pour ceramic slip (liquid clay) into the mold and let it set up. Then you remove the piece from the mold. At this stage it is "greenware" and is VERY delicate. The greenware will have imperfections on it, either from surface bubbles inside the mold or from separation lines of the mold. These need to be cleaned & repaired before you put any underglaze (paint) or glaze on and fire the piece. Cleaning is done with various tools like miniature scrapers and dental picks and with various grades of "sandpaper" (3M non-metallic brillo pad stuff, etc.) Pits and bubble marks are filled with a little of the slip mixture. All this chipping and sanding create very fine ceramic clay dust but is really essential to producing a fine looking piece. Any imperfections in the greenware only seem to get magnified when you glaza and fire a piece and once a piece is fired even if you haven't glazed it yet, you'll never get the imperfections out.

I think your idea of an air flow table would be excellent for both ceramic dust control but also for when you do stained glass. The fumes from soldering lead cane and the associated flux are probably more noxious than what comes outgassing from firing glazes in a kiln.

[Gatorboy]

All I can add is that my mother has a kiln, and it is located in a corner of the garage.

[egon]

Perhaps check with the local building inspector and insurance company of what is required to meet code.

Some low fired glazes have toxic metals in them although most have been eliminated from the market.

We have two electric kilns downstairs and a high firing gas kiln in its own metal shed in the back yard.

Your wife will also need storage space for the glazing materials, molds and greenware drying space. I speak from knowledge here as I once lost all the garage space to just such a project.

She may also need protective eye wear and some pretty heavy duty gloves if she has to pull plugs and see if the cones have gone over.

Egon

[WVBill]

"Your wife will also need storage space for the glazing materials, molds and greenware drying space. I speak from knowledge here as I once lost all the garage space to just such a project."

Oh yeah - I forgot that part. Shelves! Shelves! and more shelves!

And another thing - you said she has molds. Well, I was lucky and my wife never got into the pouring end of the hobby - always bought her greenware from the ceramic shop. But I've seen pouring done and "it ain't pretty".
Needs a special pouring table that is supposed to catch all of the overflow of the slip from the molds and re-cycle it. But the pouring areas in the shops I saw were splashed all over with ceramic slip. IMHO, it looks like pouring molds is something that really should be done in a separate room that can be hosed down occasionally.

[egon]

Just wait. If it gets serious you are going to be a man with a lot of renovations to accomadate the process. Pouring slip into the larger moulds requires some serious strenth so you know who will do that.
Then there comes a time when the product will be considered marketable and more time will be spent at craft fairs/sales. The product must be packed, hauled, set up at the sale and when all is over the reverse process takes place.

My wife makes high fired hand built pottery so there are no moulds involved.

Egon

[Pat]

Gatorboy, Given what has been discussed, I hope the garage is well ventilated when/if she does anything that produces toxic outgassing. Your father made a very fortunate discovery in your mother. My wife is somewhat more difficult to please.

Pat