“I've made this stencil out of rigidized SilkeMat. Can I fill it with powder and/or frit and leave the stencil on the glass when I fire it to a full fuse?“
SilkeMat is thicker,
with greater insulating properties than shelf paper. The base glass will be
insulated in two ways. The frit in the spaces of the stencil will insulate the
heat from reaching the base under it. The SilkeMat will have even greater
insulating effect on the glass it covers. So, the proposed layup would create
three heat areas on the base layer - the area insulated by the SilkeMat, the
portion under the frit, and the uncovered areas. These three heat areas are a
big problem for the glass to cope with, as they each will heat differently.
 |
| An illustration of cutting holes in SilkeMat to form a stencil with thick edges Credit: Katie Chapman (not the origin of the question) |
At full fuse the SilkeMat
or any other refractory fibre blanket will mark the glass and may stick in
parts. Adding weight will only increase
the marking and sticking, as well as further insulate the covered area. The most important problem with
leaving refractory papers on top of the glass during a full fuse, is the
insulating property of SilkeMat or any other refractory fibre paper, creating
large temperature differentials, which require extremely slow heat ups, long
anneal soaks, and very slow cooling. If it were to be fired with refractory fibre paper on
top, in spite of these warnings, I would fire it as though two inches thick.
A much better approach is to make a
card stencil that is stiff enough to lift easily without spilling any excess
powder as it is removed. Apply multiple
thin layers of powder, firing between each application. Careful application and firing to a low
temperature tack fuse each time will give a crisp edge to the powdered
image. This can be glossed with a full
fuse firing after the last application.
A silicone rubber colour pusher or stiff
brush can move the powder, either to the powder image or away and off the base
to give a crisp edge to the image.
If you have not already built the
piece in the kiln, powder and frit are heavy enough that they will not be
disturbed easily on the way to the kiln. An aerosol adhesive that drifts down onto the
powder will be enough to hold it in place if concerned about movement.
But best of all, is to create a powder wafer where the thickness and crispness of the image can be controlled, and then placing it onto the base glass. This avoids the risks of temperature differentials being created by the refractory paper
No comments:
Post a Comment