SpeedFire Cone System

I’ve been getting lots of emails asking me if my clay can be fired with the SpeedFire Cone system. My answer was always “Unfortunately not,” because the SpeedFire system has no digital controller, and there is no way of knowing how much gas is left in the tank. “Unfortunately,” because not everyone can afford a digital kiln.

I’ve just come back from teaching a 4-day workshop at The Greater Philadelphia Metal Clay Guild, hosted by Holly Gage. Holly had the SpeedFire Cone system and thought it might work for firing base metal clay. It was totally her idea. I thought: what is there to lose? And we tried. Before I go on, please bear in mind that I am not recommending anything, at least not yet; I am just telling what happened.

While I was teaching, Holly was reading the instructions and setting up the system. I prepared 3 test pieces. Two of them I made according to the suggestion for test-firing in my Instruction Manual, and the third was a cane-slices piece, about 10 cards thick.

We did not use the cone system as instructed. We removed the screens, and fired inside the cone rather than on top of it, with the bowl sitting directly on the burner. We used a little stainless steel bowl (typically used for cat food), filled with carbon. The pieces were positioned vertically in the bowl.

Bowl on burner, front view

Bowl on burner, top view

We put the cone on top of the bowl and turned the system on.

Cone on bowl

We tried to set the temperature for the first phase. After the pyrometer reached 1000°F/538°C it suddenly went back to zero, and we realized that the metal wire that connects the thermocouple to the pyrometer had melted. So, we removed the pyrometer and the thermocouple altogether.

After 30 minutes we turned it off and let it cool down. That didn’t take long. Then we proceeded to the second phase, and fired for 2 hours. There’s no telling what the temperature was. The valve of the gas tank was open all the way. Since this tank is supposed to last 3 hours, it seemed the appropriate amount of time for a full firing cycle.

Here are the results:

SpeedFire results 1

SpeedFire results 2

Full sintering, no under- or over-firing. What a surprise!

There is a lot to be tested yet. I am wondering whether this kind of firing can be done in just one phase. I also don’t know whether the temperature can go high enough for firing steel clay on its own, or how to regulate the temperature to fire White Bronze. If you have the cone system, it will help a lot if you do some experimentation. The more information I have, the better I will be able to report reliable schedules. By the way, this system fits the blue propane tank as well. I just don’t know yet how long it will last. To reach higher temperatures, we can try Mapp gas; this tank fits as well.

Now for a pre-announcement of a future class. Holly Gage will be coming to my studio to teach two different 2-day workshops. Between our schedules, one possible date is in February. Valentines Day is on February 14. What I am asking now is: Who would like to take a class but CANNOT make it on Valentine’s Day. (The class is over by 5pm so there’s still plenty of time to celebrate.) Please email me directly with your answers: hadar@pacbell.net. More details to come.

14 Responses to “SpeedFire Cone System”

  • Anita Leclercq Says:

    Always something new with you. Always exciting to hear about and learn.

  • Seb Says:

    This is great to hear. I still have not bought a kiln, but I have a speed fire kiln.
    Thank you Hadar

  • carol douglas Says:

    How exciting. Something new to explore
    Well done Holly and Hadar
    Thank you for experimenting on

  • Holly Gage Says:

    I so enjoyed our visit together Hadar. Chris commented we looked like two mad scientists stirring the blew.

    One thing not shown in the pictures was a kiln shelf placed on top of the cone during firing. With a bit more experimentation, this looks promising
    ~ Holly

  • Hadar Jacobson Says:

    Holly, next time I hope Chris takes photos of us wearing witches’ hats. Woooo ……scary…..
    I will post a follow up on the kiln shelf. Stay tuned.

  • Ron Taylor Says:

    Will the cat food bowl work as well in the kiln? I’ve looked everywhere for the stainless steel bowl you recommend, but have been unable to find it. I haven’t been to PetSmart yet. Thank you. Ron

  • Hadar Jacobson Says:

    Ron, yes, it will. I found it at Target. less than $1.

  • Ron Taylor Says:

    Thanks, Hadar. I’m on my way to Target.

  • maneki Says:

    Interesting read. Alternative ways of firing that doesn’t require a kiln is something I’d be most interested in as I like the look of base metal clay, but can’t afford a kiln, nor is there anyone I can borrow one from. Alas, steel clay is the clay I’m most interested in and from what I read it wouldn’t be as easy to fire in another way as copper alloy clays…

    I’ve seen that Art Clay has made a system to fire their copper clay in a vaccuum plastic bag in their art box for microwave ovens. Not very practical for big things, but for a novice like me it sounded like an option. Anything you’ve ever tried or any of your costumers using your clay?

  • facciafelice Says:

    You two are adventurous! Thanks for sharing.

  • Barbara Carter Says:

    I used the speedfire cone as you experimented with a dry inlay of bronze in copper earrings. It overfired slightly but many people who see the earrings like the raised look! I am wondering whether to turn down the value or shorten the time of the second firing the next time. Maybe it is easier to save my pennies for a kiln!

  • Hadar Jacobson Says:

    Barbara, I found that I had to turn the flame down to avoid over-firing. However, when I fire 3D pieces, the bottom doesn’t seem to sinter.

  • Anita Leclercq Says:

    I plan to buy a speed fire cone system for the first firing. We used to vacume off the ash after the first firing. Your instructions say cover with carbon and proceed to second firing. Do i just leave the ash in there? If so can i reuse that carbon?

  • Hadar Jaobson Says:

    There will be no ash after firing on a stove top. Just add carbon and continue to second phase.

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