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!

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