Many times, exact dimensions of the final piece are
not critical. When they are and the
piece is 9mm and thicker, or has irregular amounts of glass near the edge,
damming is required.
If the dimensions are rectangular,
you can use straight edged refractory materials, usually sawn up broken kiln shelves, vermiculite, or fibre board strips.
These need to be kiln
washed and lined with fibre paper. The
dams should be lined with 3mm fibre paper that is 3mm narrower than the final height of the piece. This allows a
bullnose shape at the edge to form.
If
the shape is a circular or
irregular shape the
dams can be made from thick fibre board or vermiculite. The lining of the dams is the same as for rectangular
shapes.
The use of 3mm fibre paper means that you have to make
rectangular shapes 6mm bigger in each direction to achieve the exact final dimensions. For circular or irregular shapes, the edge will need to be only 3mm larger. This is because the edge goes around the whole shape, rather than only one side.
I always appreciate you knowledge. Have you thought about trying SilkeMat for damming? It's very versatile and so easy to use and store, with no toxic particuls to worry about.
ReplyDeleteI have not tried it as yet. Only recently have I been aware that it is available in the UK. It does look highly textured. Can it be smoothed after hardening?
DeleteDo you kiln wash fiber board or vermiculite?
ReplyDeleteI tend to kiln wash both. It is not really necessary on fibre board, but absolutely needed on vermiculite. Of course, if you harden fibre board, kiln wash will be needed as separator.
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