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Fire Me Up! The Latest Firing Of My Fibre-lined Gas Kiln

Fire Me Up! The Latest Firing Of My Fibre-lined Gas Kiln

I’m still in the glaze testing mode!  Does that EVER end?!  I just want the PERFECT glaze combination and PERFECT reduction and PERFECT colours!  Actually, I want at least ONE gorgeous piece out of this firing!

So the kiln is stacked.  I raised the bottom shelf about 4 inches to see if that makes the lower shelf reach temperature – which it had not done in the past!

This firing started at 9:45 and ended at 10:00pm-so right at 11 hours.  I started reduction at 850 degrees celcius – hoping to get reds!

Although I tried to keep the kiln in reduction the whole time, the kiln stalled out at 1250 and then dropped back to 1216. So I added more oxygen and dropped back the reduction.

The flames coming out of the top of the kiln were both green and yellow?!  I didn’t know what that meant and was hoping for the best.
Because I placed the cone packs in bad viewing spots, I could only see the top peep hole cones.  Although they bent, I kept the kiln going til I got it back to 1276.  I should have stopped it when the cone 10 cone bent totally, but depended on the pyrometer and that was a mistake!
The results showed that we didn’t keep the reduction and the glazes were “over-fired” – glazes almost melting off the pots and “boiling” glazes that never settled back down.

I did, however, get some good results!  I guess that is the way we have to look at it – hoping for at least a few good pieces!  Else I’d go crazy with frustration!!!

Here’s a bowl that has been retired.  Initially, it was mid-fired to Cone 8 in an electric kiln.  I wasn’t happy with the results, so added some glaze and retired it.

Here’s the outside of that bowl – I added a rutile blue to the previously fired glaze.

This is a lovely little dessert set with a tenmoku glaze.
This is a funky little cookies and milk set.
So, all in all, I got a few pieces that I liked, learned a lot, and will refire many of the pieces soon!
Written by Marian Williams

3 Comments

  1. Ric Pierce · May 25, 2012

    Marian, from what I can see from you images of your firing….
    1.The lack of a bag wall would make it difficult to get reds on the flame side of the kiln at the best of times.
    2. 875 is too hot to start the reduction unless your temperature probe is in a very hot spot in the kiln and the rest of the kiln is a lot cooler.
    3. Green in the flue flame is not good news. Did you reduce the primary air on the gas burners to produce a nice yellow flame? I check my burners every few months on full power with the door open to see if the gas is burning with a longish slow yellow flame.
    4. I agree that the glazes look well over fired.
    5. Reduction after 1200 doesn’t add anything to my pots so i don’t waste sleep time here.
    Regards Ric Pierce

    • Marian Williams · October 21, 2012

      Hi, Ric, I’m progressing nicely with my firings, but have a few more questions, if you don’t mind answering them.
      1. Do you leave the top or lower bung open? and do you leave it open the whole time you are reducing?
      2. Do you let the kiln go back into oxidation at the end? Some sources say this is important to clean up the glazes, but I don’t want to lose the reduction that I’ve worked hard to get!
      3. My husband was going to rework my gauges and valves to the propane tanks ( I bought my kiln off ebay and everything is OLD!) and then a guy at the store (thank goodness!! ) convinced him that this was not wise-he was doing it wrong and to get a professional gas installer guy out.
      Anyways, what pressure do you look for at the tanks and at the burners? Do you use two gauges?
      Wish there were a great recipe book on this, but seems it is different with every kiln and you learn by “doing”! So, if you can help to answer some of these questions, that would be so helpful!!!!
      Thanks,
      Marian

  2. Marian Williams · May 26, 2012

    Hi, Ric, Thanks so much for your comments! Obviously, I have a lot to learn! I don’t even know what a bag wall is, much less where to put it or how to use it!

    If you could look at my latest post which is a video of my latest firing, you can get an indication of the results that I got. Reds, but runny!!! I’m learning a lot, but it can be frustrating! I used cones-the top cones when over, but the kiln said 1250 and I couldn’t see the middle cones as the bung hole is the one that I kept open and they were in that view, but fell to the side and stuck on a kiln stilt! So I overtired once again!

    As for the green, I did, this time, adjust the O2 at the burners and got rid of the green. So I had good reduction.

    Thanks for your invaluable assistance!
    All the best,
    Marian

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