Little Boxes

I seem to have moved one more step forward on the ongoing path toward better sintering. I was thinking about the analogy of “twins in the womb” and how to extend it to apply it to pieces in the firing box. If twins in the womb steal nutrition from each other, could that be what happens to pieces in the box? If each of them had its own separate space, would they not manage better somehow?

I usually avoid placing a small piece next to a big one, since in my experience, the small ones do not sinter properly. This seems a bit counter-intuitive, since I would expect smaller pieces to sinter better. However, statistically this is the case, and it may be because the heat flows towards the bigger and heavier pieces. So theoretically, if we surround each piece with an insulator such as fiber paper, the heat may not be able to flow from one area in the box to another.

I made a small box from fiber paper for every piece I wanted to fire in a single batch. I filled the kiln with more pieces than I usually do – each in its own little box – and included small, big, and hollow forms of copper and bronze. I used my regular firing schedule for Quick-fire Copper and Bronze, and all sintered beautifully.

Here is how to make the box:

Use fiber paper, ⅛” thick (cheap, and available from glass fusing supply stores). Cut a square.

Cut squares at all 4 corners, each about 2″ square.

Fold the wall upwards and staple.


Make boxes of varying sizes for different-sized pieces.

Fill half of each box with carbon.

Place the pieces in the boxes and fill the boxes to the top with carbon.

Fit as many boxes as you can in the kiln, avoiding the center. (Or could it be that with this method, there is no need to avoid the center of the kiln? I tried it once, and it worked!)

I have fired three times so far in the same boxes, and both the paper and the staples are still intact.

Here is another option: use the fiber board box that I described in my last blog posting.

Cut strips of the same fiber paper, about 2″ wide, and use them as separators.

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