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Terracotta container for sintering Copper Metal Clay?

Hi, I’m new to this forum and would appreciate some advice as to the options of containers for kiln- firing metal clay, particularly copper metal clay.
So far I have been advised that a stainless steel container with lid is the go-to receptacle for containing the activated coconut carbon that is placed below and above the piece being sintered; however, a stainless steel container will also produce firescale and mess up the interior of my [so far] well used but very clean kiln. I’d like to know if I could use an unglazed terracotta pot [of the pot-plant variety] with a lid of the same material for the sintering process?
Would the pot stand up to the temperature of between 970C/1778F to 980C/1796F?
Any advice will be most appreciated.

I haven’t worked much with PMC, but have an unused PMC3 Hot Pot Kit. It contains the hot pot kiln with a tiny terracotta pot to hold the fuel; but I am not allowed to ship the fuel bottle. I am willing to sell it for $10 (plus shipping), I believe it uses gel fuel that you can buy at large retailers.
Email me at

Why not make a envelope out of kiln paper or blanket and place the tin inside? FYI, I would only do this in a burnout kiln, not an enameling one. I understand that not everyone has the luxury of two kilns, but I got another one just to avoid this dilemma. I don’t want to contaminate my enameling kiln with all the firescale or the carbon smoke.

Hi Deborah,
Thank you for that suggestion, and it is a possibility, however you have hit the nail squarely on the head! My kiln is my enameling kiln and that is precisely why I am hesitant to go with the stainless steel containers. However, you did give me an idea, which is to investigate the possibility of a much smaller kiln for only firing metal clay.
Thank you for taking the time to give me advice. Much appreciated.

Hello Jean-Marie,
Many thanks for your offer and I am tempted, however I will need to investigate the freight options as I live in Australia!! I will also have a look at what is available from jewellery suppliers in the way of kits.
Kind regards

I don’t think you’ll get too much contamination if you put it in a envelope. Consider this: the stilts we use for enameling are stainless steel. I’d worry more about smoke. Why not do an experiment with a torch and put some activated coconut carbon in and see if your stainless steel tin is airtight. The point of the tin is to create a reducing atmosphere to burn up the oxygen in the tin, so if no smoke is escaping it probably won’t do any damage to your kiln. If I only had one kiln (and really wanted to work with the copper metal clay) I’d risk it. You can always vacuum your kiln and do a layer of kiln wash to make sure it’s clean afterwards.

You might want to check out the website of the Alliance for Metal Clay Arts Worldwide…

They have a lot of info…

  1. I fire base metal clay and sterling metal frequently. I use a stainless steel “tool wrap” that I order online and make my own containers and lids. It is a very thin ss. It hardly spalls. (not all ss spalls badly) I will go months without cleaning ss flakes from the floor of my kiln. it has no impact on the firing of any form of metal clay because I fire on kiln shelves and not the floor of the kiln. When I enamel, HOWEVER, in that same kiln, I give it a thorough vacuuming that results in a kiln suitable for enameling. no spall is ever interfering with enameling since I have cleaned it out.
  2. I think flowerpots may be a bad choice for a firing vessel. they cannot take any kind of temperature change and will certainly crack over numerous times of use. As in any jewelry technique, you want to choose the proper tool or material. Don’t try to cut corners here. After you have spent money and time making your metal clay piece, for goodness sakes, it’s not great to have the firing screwed up because of the wrong container.
    some advice on making a tool wrap firing box: wear gloves, it can have sharp edges, to make a box I use the same technique as when I was a kid and made constrution paper Easter baskets. If you can’t visualize this, email me and I will elaborate. by making every box tailored to the piece you are firing, you have less waste of carbon, more even heating and sintering, and less hassle overall.
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Hi—I’ve been a metal clay teacher for over 15 years. I highly recommend that you stick with stainless containers. Clay doesn’t transmit heat well, and can affect sintering. One great option for a flake-free container is stainless foils/thin sheet. (try Cool Tools for that).
Be careful—it will cut you if you aren’t careful.
I have used steel cans for small pieces, but there are issues with that as well: plastic lining burnout, especially.
My kiln gets dirty with base metal firing. I brush it out and vacuum it, and use kiln shelving for silver work.