Shortening the Firing Time – Follow-Up

There have been a lot of responses and questions about my last posting about shortening the firing time and I’d like to address them here.

First, I must say that I’ve never gone back to firing the first phase in the kiln. Firing on a camping stove, kitchen stove, or the SpeedFire® Cone System™ for Metal Clay seems to work 100% of the time. The advantages:

1. It saves a lot of time. The firing time is practically the same as firing silver clay.
2. You don’t need to worry whether you held long enough at the first phase. When the smoke is gone and the pieces darken, you can be sure that the binder has burned off completely.
3. No need to cool down between phases.
4. In a workshop situation, a lot more pieces can be fired.

Again, this way of firing replaces the first phase only. Once the binder has burned off, the pieces need to be covered with carbon and the box should be moved to a kiln for the second phase.

It’s been reported that an electric kitchen stove works just as well. It makes sense: when the pieces are not covered in carbon, the binder will burn at 400-500F, which is within the capacity of an both electric and gas stoves.

As a lid you can use just a fiber board or fiber blanket with a hole These photos were missing from my last posting.

Top view

Fiber blanket

Watch for the smoke coming out of the hole. If you are not sure (sometimes thin pieces don’t generate a lot of smoke), it is ok to remove the lid with a glove or tweezers to look for the smoke and the color of the pieces.

I have successfully fired big and hollow pieces, including rings. My advice: with complex pieces use low heat; it’s best for the binder to burn out slowly. Still, the firing time rarely exceeds 10 minutes. (Rings need to be positioned in a special way. I will talk about it in my upcoming workshops).

And finally – this works with all base metal clays: bronze, Rose Bronze, White Bronze, copper, and steels.


41 Responses to “Shortening the Firing Time – Follow-Up”

  • Ellen Goldman Says:

    Dear Hadar,
    Thank you for all the know-how you are sending to the users of your books and blog.
    During my unniversity years (I read chemistry) we were trained how to run tests and I have used many of the techniques learned so many years ago in my works as enameller/metalsmith.
    I find your way of working fascinating and the fact that you take a ,lot of experimental work out of our hands so that we can move on so much faster than normally is uplifting and wonderful.
    Thank you,
    Ellen

  • Kathy Scofield Says:

    Dear Hadar,
    I have made some of the mini kilns out of soft firebrick. Do you think one of these would hold up on the kitchen stove with the direct heat?
    Thanks so much,
    Kathy

  • Tana Says:

    I just want to say that since reading your first posting about this I have used this method on my last two firings and it works beautifully! It is now the only method I will use for first stage firing. I am so impatient waiting to see how all of my pieces turn out, I am surprised I don’t sit and watch my kiln! This is so much closer to instant gratification! Thank You!

  • Jackie Schubbe Says:

    Would this work on a gas grill?

  • Georgie Galante Says:

    I tried a gas grill yesterday. It did not work for me – I think because the flame wasn’t directly on the ss-bowl or at least closer too it. There wasn’t any smoke or odor. It was about 30 minutes. The bowl vibrated, but that was about it. I moved the bowl to the single electric range and there was smoke and odor. Worked perfectly again.
    Hadar: On the second phase, does the kiln have to cool down completely with the fired pieces in it or can the bowl be taken out once the 2 hrs. are up?

  • Teri Says:

    Hadar, if I followed your description correctly, then it is better to NOT conduct the first firing in the kiln since this tends to weaken the metal (oxidation that cannot be seen). Or is it still OK to conduct all firings in the kiln if we do not have access to this additional setup?

    TIA.
    Teri

  • Hadar Jacobson Says:

    Kathy, I don’t want to say without trying it myself, but I am guessing it’s ok.

  • Hadar Jacobson Says:

    Jackie, I don’t see why not.

  • Hadar Jacobson Says:

    Georgie, No need to wait. Just be careful: it burning hot!

  • Hadar Jacobson Says:

    Teri, It is ok to conduct the first firing in the kiln according to the old instruction, meaning that the pieces should be covered with carbon. I don’t recommend doing this without covering with carbon.

  • Sarah Triton Says:

    Hi Hadar:
    I wish I had a nickel for all the times I’ve thanked you for your generosity, I could buy a “can” of clay. Anyway, I’m thinking of making a cuff using my PPP monogram method. Will that be too large a piece to firethis way? Also, I know that if I use steel, I have to form it and let it dry thoroughly, but will it hold up as a cuff? How about bronze or copper…form it first or will those be bendable after firing?

    Thanks so much, as always,
    Sarah

  • Susi Says:

    Thanks for the update Hadar. Have you ( or anyone else) tried this with an ultralite beehive kiln? They should reach the recommended temperature (400-500 degrees) easily. The lid is already vented but it is metal so maybe I should use fiber board with a hole?

    Thanks, Susi

  • Bernadette Says:

    I have a Speedfire super Mini. Will that work for the first firing?
    Thanks,
    Bernadette

  • Hadar Jacobson Says:

    Sarah, I think it’d be ok if you do the first phase on low fire. Steel would hold as a cuff, but when you form it over something it may crack since it shrinks a lot while drying. Bronze and copper should be ok. I always form first. That’s the big advantage of metal clay, being able to do all forming and joining before it turns into metal.

  • Hadar Jacobson Says:

    Susi, I haven’t tried but it seems possible. I would try first with the existing lid. Please let us know!

  • Hadar Jacobson Says:

    Bernadette, It will work id the butane tank will last 10 minutes.

  • Marie Says:

    Hello Hadar,
    I’m a newbee to your base metal clays and have so far done one test firing using your original method with my brick kiln. I want to try your suggested method to shorten firing time. I have a question regarding the picture above (on the camp stove)…. is that a stainless steel bowl placed directly on the burner?
    Thanks so much,
    Marie

  • Hadar Jacobson Says:

    Marie,
    Yes, that’s what it is.

  • Shelly Rewinkle Says:

    Hello, I am very new to PMC but have been using the Bronze only so far…I tried the shortened fire method on 1″ pieces 6 cards thick and it worked great! Now, I have two pieces 3″ and 8 cards thick and after the stove top they were warping….any suggetions before they go in kiln? Ok, they are already in the kiln and hoping they will “fix themselves” method I assume will not work 🙂 Thank you very much, this blog has been a world of help!

  • Hadar Jacobson Says:

    Shelly,
    It may fix itself if you turn them upside down for the second phase, but I am not really sure. Next time, when you have thicker pieces, do the first phase on very low flame to burn the binder a little slower.

  • Jennifer Says:

    Has anyone tried simply doing a short uncovered phase at 500 degrees in a regular kiln? To clairify, I mean setting the pieces in top of the carbon ramping full to 500 with a 5-10 minute hold, then covering them with carbon and doing the second phase regularly.

  • Hadar Jaobson Says:

    Jennifer, I don’t see any problem with that as long as you put the pieces inside the kiln after it had reached 400-500 degrees. The idea is the minimize the exposure to air, and with kilns that take long to ramp, it’s going to be a long exposure.

  • Jennifer Says:

    I may just have to try that with a few scrap pieces. I’ll let you know how it works out!

  • Marie Says:

    Hi Hadar,
    I’ve completed a couple of test firings an am happy to report that the first phase seems to have produced good results using carbon in a stainless steel bowl covered with a thick fiber blanket and fired on an inexpensive single electric burner. It took a bit longer than 10 minutes, but I think that may be due to the burner taking a few extra minutes to get to high heat.

    I do have a question regarding the 2nd phase firing in my brick kiln… As suggested I made a couple of test pieces using copper as the base and a couple with bronze as the base. The pieces with copper as the base are coming out flat and relatively flush. The bronze based pieces are slightly curved and raised where the copper is. I reduced the temp by 10 degrees (to 1460) and got the same result. Should I reduce the temp even further?

    Thanks so much for your support!
    Marie

  • Hadar Jaobson Says:

    Marie,
    That’s not a matter of temperature. When you use an overlay technique, always use copper or mixed clay as the base. Bronze shrinks more and therefore bends backwards.

  • Marie Says:

    aaah..mystery solved..thanks Hadar!!
    Marie

  • Rachelle Says:

    I am very new to metal clay. I have an electric glasstop stove. Would phase 1 be safe for that? Also, since I have a very small kiln (6″ x 6″ top-loader), my SS container is a 5″ round one and only about 1″ deep. I cannot find any others small enough for my kiln. Is that OK?

  • Hadar Jacobson Says:

    Rachelle, I can’t think of a reason why it wouldn’t be safe. There will be some smoke. As for the kiln, the smaller the better. Just make sure the pieces are all covered with carbon at the second phase. Also, do test firing to find out the right temperature for your kiln. The instructions are in the instruction manual on my blog.

  • cindy smith Says:

    Hadar – I really like this new technique for first firing. Used this week and it worked like a charm. Out of the batch of 20+ small bronze items I fired, a few developed an unusual pale yellowish colored oxidation while all the rest were the normal dark brown. When buffed, the light colored pieces were much brighter than the others but show no other differences. I can send you pictures if you’d like to see.

    Have you experienced this?

    Thanks very much.

  • Hadar Jacobson Says:

    Cindy,
    Please do send me pictures. I’d like to see.

  • ann schneider Says:

    Hadar, I cannot even begin to thank you for all the work you do. This is fabulous and I am trying it this week.
    So grateful.
    ann

  • Holly A, Black Says:

    Hadar, Sorry to be redundant but I just want to make sure I have this correct! I don’t have a Speedfire Cone thing but we might have a camp stove out in the barn. I already was going to ask about the gas grill but saw where that was a nonstarter. I really don’t want to do this in our kitchen but is a old fashion electric ‘hot-plate’ – single burner sufficient for a stove? Naturally anything that will speed up firing time is a plus. Thank you for your dedication to perfecting this medium & helping us along in this beautiful craft.
    Blessings,
    Holly

  • Hadar Jaobson Says:

    Holly,
    People say the electric stove works for them. It depends how hot and how quick it gets. A simple camp stove, single burner, ($10), will do.

  • Kari hill Says:

    Hi Hadar- I was wondering if the reason my bronze pieces were breaking in half was because I have a paragon bluebird that heats to 1200 degrees?

  • Hadar Jacobson Says:

    Kari, 1200 degrees is too low for bronze. Please have a look at the instruction manual on my blog. You will find the firing schedule that applies to your kiln.

  • Marla Kutzer Says:

    Hadar, thanks for all your help. I would love to see you add the firing schedules for firing peices of just one type of clay, no combinations. Sometimes I just want something simple, like charms or earrings out of just one kind of clay. Like an entire load of copper pieces. Also if anything special needs to be done to fire for example a copper piece along with a bronze piece. Two separate pieces in the same firing to save on time and electricity. I don’t think this has been posted, if so I guess I have missed it.
    Thanks, Marla

  • Billy Zeemann Says:

    Hi Hadar,
    I just wanted to let you know I successfully fired my first test pieces of your Pearl Grey Steel XT using the quick fire method last night. I did the first phase on my kitchen stove and to be honest I wasn’t watching it the entire time as I was up and down from the computer…so, because of this I wasn’t 100% sure of all the binder had burnt out so I left it going for about 15 minutes. Then I covered it with more carbon and fired it in my front loading paragon kiln at 1860 (my kiln appears to be running approx 100 degrees low so I have to raise the temp for everything accordingly). In any case I am very happy to say if fired beautifully and I love the shrinkage factor! …I used to love working in PMC standard because of the shrinkage for its ability to capture fine detail so well so I’m happy this clay will work out for me!
    ps I did the kiln phase with no lid…is that correct? It is just so messy with carbon everywhere I was thinking my next batch I’ll cover with a lid…any thoughts?
    Thanks Hadar!

  • Hadar Jacobson Says:

    Billy, Right, no lid. The carbon is not what makes the mess. It’s the ss bowl oxidizing and flaking.

  • Hadar Jacobson Says:

    Marla, Open the manual from my blog page. You will see that there are firing schedules for every metal, not only for combinations.

  • Marlynda Says:

    Here’s a quick but huge THANKS for all you shared at the Dallas class at the PMC Connection. I am preparing for a class I’ll teach in a few weeks and I am wondering what experience you had or if you tried doing the first phase firing with the piece sitting on carbon being fired with a butane torch? I use the Max Butane Torch with lots of fuel. I’m thinking of this not for a class, but for students working a home one or a few pieces at a time.

    Also is there an advantage to either the single burner camp stove on top of the fuel tank like we used in Dallas or to the two burner camp stove which you have pictured in your blog on several occasions? At our Walmart, the two burner stove is less than 10 dollars more than the single burner which is about 24 dollars. In a class setting, the two burner might be a good idea.

    Thanks again for doing all of the endless experiments you do, saving us time and headaches. Your open hearted sharing is a rare gift.
    Marlynda

  • Hadar Jacobson Says:

    Marlynda, Firing with a torch causes cracks in the pieces most of the time. The pieces should be smoking, without being set of fire. A double burner is great. You can also connect to it with an adapter a big gallon of propane. Probably cheaper then the disposable ones. Good luck with your class! I had a great time with you in Dallas.

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