A Wish Come True

You may remember my blog post from a while ago, titled “Please Make Us a Box!.” It seems that my wish somehow came true. PMC Connection have just released a fiber firing box.

When I ordered it, it was already out of stock and I had to wait for a new shipment. Since I received it I’ve been able to do some experiments, and I’d like to share them with you.

The box is round, 6″ in diameter. It fits perfectly in my 6.5″ x 6.5″ x 4.5″ kiln.

I have plenty of room to take it out of the kiln hot using heavy-duty heat-protective gloves. I filled the box with more pieces than I usually do, placing pieces in the center as well as on the sides, and everything sintered perfectly.

By the way, this small kiln is my favorite. I think that for jewelry, the smaller the kiln, the better. Good distribution of heat, no waste of energy on heating just air. I just wish it were round. In my opinion, the circular shape of the box helps with even distribution of the heat.

Here is how it fits in my 8″ x 8″ kiln:

Again, I filled the box. In the center I placed 2 pieces, 4mm thick (about 15 cards). The rest of the pieces are about 2″ x 2″.

The thick pieces in the center fully sintered.

As you may remember, I never fire in the center in an 8″ x 8″ kiln. So, in spite of the smaller size of the box, it can be filled with almost as many pieces as a bigger box.

Important notes

1. If you fire in these boxes, you need to lower your sintering temperature (the temperature of the second phase), or your pieces will be over-fired. I lowered mine by 30°F/17°C in all three of my kilns.

2. The boxes hold the heat for a long time after the firing is over. That means that it takes them longer to cool down between phases. It also means that if you fire overnight without a lid, a lot of carbon will be burnt. My suggestion is, use the lid that comes with the box, but first drill a hole in it, about 1″ in diameter. That will reduce the amount of burnt carbon while letting all binder and contaminants escape. Without the hole, the carbon may not be able to burn, which helps to create a reduced atmosphere.

I am curious to know what happens if we set the kiln to fire one hour instead of two in the second phase. If the boxes stay hot for so long, maybe we can leave them in the kiln for the second hour with the kiln off? I’ll try it when I get the time. If you try, please let us know!


26 Responses to “A Wish Come True”

  • Lynn Latta Says:

    I have the fiber pot but have not used it yet.
    For bronze I have been using bisque pots ( I use a saucer as a lid) which have been holding up for many firings. Copper is too hot and they crack. However I have done firings for bronze and hold for 10 minutes and they have fully sintered. This works for pieces no thicker then 4-5 cards thick.

  • Linda Reboh Says:

    There is a small kiln manufactured to fuse glass and sinter PMC in the microwave. I wonder if this could be used with the carbon in the kiln?
    Many of my students use it regularly to fuse glass. Should I try it? Would it cause any damage to my kiln. I believe it is completly made of the same fiber used in kilns. I know that Delphi Glass sells them I will call and ask.

  • Hadar Jacobson Says:

    Linda,

    In order to fill this box with carbon you will have to turn it upside down, right? Is it possible to fire like this?

  • Karen Richard Says:

    Just ordered mine, thank you Hadar! Sooo I have to turn this thing upside down..is this cuz it does not come with a lid????

  • Karen Richard Says:

    OOPS I should have read your blog…sorry got it!

  • Leslie Scott Says:

    I spied & ordered these fiber boxes when I got the e-mail weeks ago from PMC Connection. I have not used the lid with my latest copper clay class’s work. But I have noticed that I have gone through a lot of carbon!! So I will try my firings with the lid. I do caution that this handy container becomes more delicate with the number of firings..so go gently with it, lifting it out of the kiln, etc. I have had uneven sintering though & have been fooling with the final sintering temperature. I work with 2 kilns–Evenheat 360 & a Paragon SC2.

  • Vanessa Weber Says:

    How do you put a whole in the lid? How big should it be?

  • Vanessa Weber Says:

    Sorry, I meant to say ‘hole’, not ‘whole’. I can’t believe I did that!

  • Vanessa Weber Says:

    Never mind, I see here that you recommend a 1″ hole. Sorry.

  • Tammy Gilchrest Says:

    Hi Hadar! What is the best way to cool down the carbon after firing? Could you pour it out on something to spread it out for cooling?? If so, what would you recommend? And also, how do you separate the spent carbon.

    Thanks in advance!
    Tammy

  • Hadar Jacobson Says:

    Tammy, After the first phase of firing I just take the box to cool outside. It usually takes 1-2 hours. After the second phase, I pour the carbon into a steel bowl through a very fine sieve. Most of the carbon stays in the sieve. The ash is so fine that it goes through the hole. If you shake the sieve a bit, more sh just disappears in the air. Then I pour the carbon into another bowl through a bigger-hole sieve. All the carbon goes into the bowl for re-use and the fired pieces stay in the sieve.

  • Pat Roach Says:

    Can’t wait to get one and try it. I saw the comment that the box becomes fragile after firings. Does anyone have the approximate number of firings that the box survives? I assume that you are placing it on posts in the kiln to allow heat all around the box? Is that a good assumption? I use a SC-2 kiln.
    Thanks for the help!

  • Hadar Jacobson Says:

    Pat,

    The manufacturers say that they have been testing it every day for months and it’s still ok. It does have to be raised. Hope to see you again in October at Studio34!

  • Linda Reboh Says:

    Hi Hadar,
    I used the box and in the first phase fired for one hour, traditional bronze with no lid. It was amazing how long it stayed hot, even putting it outside after four hours was still hot.
    I took the pieces out and they were very hard. I should of rinsed one to see if it sintered all the way but its a student’s work and didn’t want to take a chance. There firing now in a regular steel sink for two hours. I’m going to do a test and do the first phase for only 15 minutes and than take it out. Its supposed to snow tomorrow, could I leave it on a counter on a fiber blanket instead of outside? After that I will try to fire it for only an hour in the second phase.

  • Hadar Jacobson Says:

    Linda,

    Did you actually moved the pieces from the fiber box to another box after the first phase?

    I think it’s ok to leave it on a fiber blanket as long as it’s at least a foot away from anything combustible.

  • Tammy Gilchrest Says:

    Hadar,

    Thanks for my earlier reply! I’m am a bit confused on the phases that you talked about. Could you direct me to any instruction that explains that? I am really looking to find out how long to fire the bronze/copper and at what tempature.

    Thank you for all of the wonderful information and instruction that you give!!

    Tammy

  • Hadar Jacobson Says:

    Tammy,

    Please have a look at the instruction manual on the right side on my blog. I believe it will clarify everything.

  • Pat Roach Says:

    Hi- I am looking forward to seeing you and learning more great techniques in October. Finally had the chance to order the box from PMC looking forward to trying it out.

  • Hadar Jacobson Says:

    Pat,

    Remember that you may have to lower the temperature with this box. Have you ever finished that mokume-gane piece? You promised to send me a photo. See you in October!

  • Carol Says:

    I am new to using copper clay and was surprised to see that you don’t use a stainless steel container to fire your pieces. How can I use this container to my advantage without having to order a different one. My supplies will be coming in soon and will be disappointed to have to exchange my steel container. Thank you.

  • Hadar Jacobson Says:

    Carol,

    First, don’t use the lid. Then after each firing vacuum your kiln because the box oxidizes and flakes and contaminate the kiln. And third, you may have to fire higher than what is suggested in my instruction manual because the box is not a good heat conductor.

  • Sutton Says:

    Hadar –

    I’ve been checking PMC Connection regularly because I would LOVE to take your class when you’re in Dallas. However, the class still isn’t posted. Do you know when registration might open? They told me on the phone it would be a couple of weeks ago. Thanks!!

  • heidi jo Says:

    Have you continued to use this box? Will you be adding instructions for this box to your manual, or do you prefer the other methods listed there.

    Also, have you tried the no-flake foil boxes offered by cooltools.us? i’m curious how that would change the firing procedures.

    thanks hadar!

  • Steve Says:

    Hi Hadar,

    We are using a ceramic firing vessel that want to cool slowly to avoid cracking. It takes over 3 hours with the lid of the kiln propped open an inch. We get a lot of ash. The vessel cam with a top. Would putting a vent hole in it and covering the pot help diminish the amount of ash? If so how large of a hole would you suggest for ceramic?

    Thanks
    Steve

  • Hadar Jacobson Says:

    Steve, The hole can be eighths of an inch (or pencil size). However, I think that switching to a different kind of carbon will be more helpful. I fire overnight with no lid at all and get very little ash.

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