Good kiln for flask burnout?

Jewelry Discussion
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I’m looking at setting up lost wax casting capabilities in my small basement studio and need a burnout kiln for flasks. I’m looking at the Xpress-E-12T model from Paragon (it’s on sale online for $963) and wondering if those with more experience think this would make a good burnout oven?

http://www.paragonweb.com/Xpress-E-12T.cfm

My thoughts in the “pro” column are that it’s firebrick rather than ceramic fiber muffle (slower to heat up but better heat retention for the long burnouts and thus less wear on the controller having to turn the elements on and off to maintain heat) and it’s got a tall chamber at 9" which would accept the largest flask my vacuum casting machine can fit (7" tall) with a wax draining tray underneath and a bit of room for air flow.

Thoughts? Does the chamber dimensions seem good to pack flasks into? Does anyone have an opinion on firebrick vs. fiber muffle for burnout ovens? Will I actually ever cast 7" flasks in my VIC 12 casting machine?

Thanks so much for your help in advance! :smiley:
-Rachel

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Rachel,
Don’t know what supply house you are looking at this model of Paragon kiln that is on sale, but Cool Tools (cooltools.us) has the same model for $899 with free shipping in continental U.S., so you might want to check them out. I don’t think it comes with the wax drain tray, although you could inquire to see if it does.

I got my kiln ( SC2 model) from these folks and have been very satisfied.

I opted for the smaller firebox because I am not casting more than a handful of items at a time so I use a 4" flask. This also cuts down on burn-out time. I am also very satisfied with the fiber-lined ovens. I have use both fire brick and fiber ovens over my many years of experience as well as several different makes. I have yet to wear out the element in my Ney Craft ovens (fiber) that I use at school, but I had to replace the heating element in my fire brick one a few times. It was an older oven, so I don’t know if that had anything to do with it, but that is one reason why I got the fiber ovens to replace it. When the time came to buy an oven for my personal workshop, I did a lot of research and decided on the Paragon for chamber size, programmability, versatility (casting burn-out, enameling, precious metal clay cintering), and ease of maintenance/repair. I talked to the folks that make the Paragon ovens. Really nice and helpful folks.

Hope this helps,
Mike

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Hi Rachel,

The paragon kiln you are looking at looks pretty good. I prefer firebricks. The extra inch of height is crucial.

Questions to additionally consider:

If your controller goes out, is it easily replaceable, repairable & can the kiln function without it? Those are important questions to ask.

I shopped for kilns starting two years before I finally purchased a kiln from Bruce at Satellite. The one I bought is about the same height & it is larger (holds 6 flasks efficiently) which for me was a huge plus. The controller I got is an Orton and stand alone unit. If the controller dies, the kiln can still be run manually with a reostat dial and temperature setting read.

I also got a shut down thermostat switch - a heat fuse of sorts (I can’t remember who makes it). If the controller or kiln exceeds my programmed highest temperature setting, it turns itself off. Its set +15 over my max. I do some cast in place gems and that’s a necessity. It also is a great safety feature. Before I built out my own studio, the studio I used didn’t have that feature, the programmer failed and kiln and controller were damaged. and all the the invested flasks were not to happy either. It was on an overnight burnout and disaster.

You will need to build some sort of efficient exhaust ventilation system over the kiln for burnouts if you are not steaming. I burn and don’t steam. Its quite stinky between 2-6 hours, more than you would ever think. I use a tall skinny flask as a mini chimney. My ventilation ducting hangs on an adjustable track overhead and never touches the kiln or flask. It overhangs the chimney flask so that no fumes escape. You can see a bit of wax residue inside the chimney on the top of the kiln sometimes.

I too have a basement studio of sorts and am extra careful (paranoid maybe) of fumes, good ventilation, fire hazards. I do have two large banks of windows, but that is not enough: mechanical ventilation is necessary.

There’s a large kiln shelf on the top of a vintage rolling tool stand (originally for a band saw I think) that the kiln is set up on. Its a great fireproof surface with a bit of extra edge for placing hot flasks as I move things around preparing to cast.

Personally, I prefer a centrifuge even though I have a vacuum caster, too.

And the electrical cord should be unplugged between uses. The cords get brittle and die for some reason (i heard that from my electrician, the kiln guy and a ceramic artist friend who it happened to.)

You are in the verge of an exciting adventure! Only time will tell if you use a 7" flask in your vacuum caster . . .

Eileen

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Hi Rachel,

First off, congratulations with upgrading your setup, very exciting!

You need to be careful when combining these two things: “Basement Studio” and “burnout kiln”.

As Eileen said, ventilation is critical. If you ever do get to using 9” flasks, a LOT of nasty fumes/gases are generated, even a small amount in the house air would make for a very uncomfortable or even hazardous evening. I use wax, plastics, resins and natural materials in my work which makes the burnout process even worse.

Adding a steam stage between investment and burnout will eliminate some of the problem but not all of it. You can steam out wax with a low-tech (dedicated) canning pot and wire rack over a hot plate.

When designing your ventilation system, making it adjustable as Eileen described is a great idea. You will also need to think about ‘makeup air’. As the fumes are exhausted from the home, where will the new fresh air come from? If you live in an older less tight home this will be less of a problem, in a new ‘tight’ home, you will need to deliberately plan for makeup air.

Ideal would be to have your casting setup in a garage or out-building (still with ventilation). Lots to think about.

Keep up posted with your progress.

Best

Mit

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Wow! Thanks Mike! That’s definitely a better price than I found.

As I’m just starting doing my own casting I’m really not quite sure what size runs I’ll be using. I probably won’t need larger flasks for the sheer number of items, but I may need them for larger individual items like the cuff bracelets I make and I don’t want to be restricted in flask size by my burnout oven. I definitely found Paragon among the most helpful and flexible of the kiln companies, I really like that they let you customize their kilns to such a degree!

Thank you for your advice and the tip on the cheap kilns at Cool Tool! :grinning:

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Thanks for your great suggestions Eileen!

It looks like mostly of the kilns I’ve been looking at have integrated controllers. I’ll admit I considered that a plus, but I didn’t consider the possibility of the controller going kaput on me… I’ll have to look into whether the kiln could be run with an external controller if the inbuilt one was to stop working, and also investigate the possibility of one of those max temp shut off switches! I’m planning a lot of overnight burnouts to take advantage of the better electricity prices and I would not want to fry my kiln while I sleep!

I’m planning on getting a system like this for venting the fumes out the basement window.

I’m a nurse by day and I’m very conscious of the various respiratory risks with metalsmithing. I definitely don’t want my house full of fumes or my lungs full of silica (I have all the respirator gear and another direct vent outside for soldering and working with investment).

Our electrician is coming to assess our wiring for installing the kiln, I’m looking at getting a dedicated circuit and maybe even hardwiring the kiln as I’ve heard the outlet/plugs can be a spot that causes trouble over time.

Thank you so much for all your great advice! I can’t wait to have my shop set up and have something successfully cast to post! :grin:

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Thank you Steve! I’m super excited to finally do my casting myself after too many mishaps mailing waxes to casters (melted, broken) and difficulty with the quality of casts (my fault? Their fault? Hard to tell when you don’t do the whole process!).

I’m definitely conscious of the dangers of my basement studio. It’s one of the main reasons I’m still working with a little Orca propane/air torch than runs off tiny plumbing propane bottles rather than having a big oxy/gas torch.

I’m planning on getting this system for venting my kiln.

Do you think this may be adequate for venting from down in the basement?
I have another homemade direct-outside venting system for my soldering bench (which will do double duty for venting when mixing investment).

The basement is open to the main floor through a good sized stairwell, I hadn’t considered that I’d need any sort of makeup air. My house is about 16 years old and I imagine reasonably tight, I hadn’t noticed any issues when running my soldering ventilation but that is for fairly short time periods. I definitely could leave a window or so open in the basement or main floor while running the kiln ventilation, do you think that might help keep air flowing?

Thank you for your input! :smiley: I feel much more prepared for this big step with all the experience here on Orchid behind me!

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In other seasons it may not make a lot of difference regarding heating and cooling your space, but in the winter particularly you don’t want to be drawing cold air into your warm space. The solution is to use a duct or make a vent very near to the kiln. That way the air is drawn into the kiln area and up the flue without circulating around the house and making it cold. The heat in the rest of the building is not disturbed. With fireplaces, folks will cut a vent in the floor right in front of the fireplace and the air goes right into the fireplace and not into the room. It is the same principle. You could make some kind of rectangular funnel to fit onto a round duct that would fit into a small window opening and then run the duct over to where the kiln is. Or just put a board with a round hole the size of the duct in the window opening. The vacuum going up the vent chimney would draw in the air from outside through the tube. At least that is how I would do it. If there isn’t much heating or cooling going on, you can just throw open a window and let air in.

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Rachel,
I also found an inexpensive alternative to the wax drip pans offered at any of the jewelry supply houses. I picked up a stainless steel drink drip pan from a restaurant supply place I found online that would fit the firebox on my SC2 oven. I paid something like $15 for it including S/H. Lot better than the $35-40 I saw for the drip pans at the jewelry supply houses.

I also have a basement studio. I got a 2 speed over-the-range exhaust hood that came with ducting hardware and hung it about 10-12” over my oven and ducted it out my slide open window. Works great! No wax burn-out smell in the shop, or upstairs.

I agree with others about safety. Since my workshop is in my house, I NEVER do a burn out over night; I am always there to monitor progress of the burn-out cycle. Maybe I’m just overly cautious, but better safe than sorry.

Enjoy the journey. Casting is one of my favorite things to do. Mike

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Hon Roy! I’m in Southern Ontario so we do have some pretty solid winters and I get what you mean about probably not wanting to just throw windows open willy-nilly. The kiln will be vented out the one window in the main part of the basement and there isn’t any other window to run a return-air into the basement near the kiln. But I’ll be think about your suggestion and see if I can rig up something to ensure I’m getting lots of reasonably warm fresh air down to my workshop. Thanks for your help with my setup! :grinning:

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Hi Rachel,
Actually, as long as you separate the ducts by some distance, I think you could vent out and draw from the same window…say you drew from just outside the window and ran the outlet out the window two feet and pointed it away from the return air duct…I think this would be enough room so that your vented air and intake air did not mix…there’s a whole lot of air outside that one window! Or just angle the ducts differently, draw from the left and vent to the right, you get the idea…

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Just a thought – I would vent to a stack (chimney) and refresh from nearer ground level. Actually I’d probably talk to my HVAC chap to make sure I got it right.
Regards RLW

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Look into a ductless fume hood.

Andy the Tool Guy

Director Tools Business

800-877-7777 Ext 4194

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That’s a great idea Mike! I came across similar steel drip trays listed on Amazon as bar supplies and wondered if they would be suitable for wax-catch trays - I guess they will, and definitely way cheaper than the trays marketed to jewelers!

I went with the vent-a-kiln system that I linked in an earlier reply for exhausting my kiln. I liked how it was table mounted giving me a bit more flexibility in where my kiln was located. I haven’t received it yet but Jay with Vent-a-Kiln was great to work with and I’ll post how it works once I have it all up and running.

That’s a good point about not burning out over night. I’d love to take advantage of the significant energy savings by running my kiln overnight but saving money isn’t worth burning my house down!

Thanks for all your help! Soon hopefully I’ll be able to say the same about casting! :smiley:

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I’ve purchased a Vent-a-Kiln system for my kiln exhaust and when talking to them they said that with the 500cfm fan in the system I probably wouldn’t need to worry much about additional vents to bring “make up” air into the kiln area as it’s in a large open basement with significant unobstructed access to the main to levels of the house. I’d prefer not to have any additional air intakes as it gets pretty cold up here in Ontario and more air brought into the house means more air to heat!

Thank so much for your advice! :slightly_smiling_face:

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Thanks for your suggestion! I went with the vent-a-kiln system and I’m having a friend who does HVAC come help me set it up and make sure it’s all working properly before I fire any equipment up. No one wants a basement full of carbon monoxide! :fearful:

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Rachel, I’m not sure we’re on the same page…if you don’t provide an intake air vent, your exhaust fan is going to draw cold air into the house through any leaks that you have. If your house is really air tight, the exhaust fan may not work right. The purpose of providing an intake air vent is to allow intake air to come in near the kiln and go directly into the kiln or up into the hood. You do not provide an intake air vent at the window, you run the duct over to the kiln. In this way, the cold air coming in doesn’t mix much with your room air, it just goes into the kiln and up the vent hood. Since the air intake equalizes the air pressure in the house, you don’t have a lot of cold air infiltration through the sides of windows and doors, etc. I hope I’m making some sense here.
Best,
royjohn

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A suggestion

When you place the vent hood, take a tin can or similar. Set a wad of paper on fire. Then blow out out. The smoldering paper will smoke and allow you to accurately test for invisible things like CO2. If the smoke isn’t COMPLETELY sucked up by the exhaust system eliminating any smoke or smell, or might need to be adjusted or moved a bit. That’s how I tested my set up and or took some tweeking to get it completely sweet! Now it’s NO FUMES ever, as long as the system is running. I had to bring my hood down a bit closer to the work area.

Eileen

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Sorry Roy, I think I maybe did misunderstand your previous post a bit. Basically the rep fro Vent-a Kiln said that with a 500cfm fan I don’t need a dedicated make-up air vent to ensure the vent works correctly (which is my main concern). Apparently a 500cfm fan is a similar size to many bathroom exhaust fans and those don’t require make-up air to run, and as my basement is a significant size and open to the two other levels of the house he felt the fan would not be moving enough air relative to the general volume of air in the house to cause a problem.

You’re totally right (and I missed the part about air sneaking in doors/windows/etc), running any sort of exhaust will encourage outside air to enter the house where it can, so I’ll have to keep an eye on my heating and cooling bills while running the kiln exhaust and see if there’s an issue. If there is I’ll definitely look to rigging up a intake vent to my kiln area to mitigate it, but as I’m relatively unfamiliar with HVAC/DIY and looking to set up my shop fairly quickly I’m hoping just my planned set up will do the trick!

All the best,
Rachel

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That’s a great suggestion Eileen, thank you! It would definitely be easier to test my exhaust system that way than to fire up the whole kiln only to find it’s not quite right when my shop is full of smoke and fumes!

Cheers,
Rachel