It
is often recommended that large bubbles can be fixed by drilling out
the hole if the raised part is thick, or by breaking the thin skin of
the bubble and filling with a piece of glass or frit.
My
experience leads me to say that "drilling and filling" is
hardly ever successful. There always is a mark where the fill has
been made, often there is a colour variation too.
There
is another possible solution for small
bubbles
which are at the surface but not yet burst.
Turn
the whole piece over and take to just below full fuse. This will
allow the bubble to begin moving to the "bottom" of the
final piece. Then flip over, clean really well and take to a fire
polish - quickly up from bubble squeeze temperature and with no soak
- to give a smooth surface, but not allowing it to get so hot the
bubble comes back to the top. This will require observation to stop
the temperature rise as soon as the surface is shiny.
Small
burst bubbles
Small
burst bubbles can be fixed by placing small “beads” of glass made
from frit in the kiln. The appropriate sized bead can be placed in
the hole and others arranged in a pleasant arrangement and all taken
to a tack fuse. The beads are made by cutting small squares of glass
5-6 mm and taking them to full fuse. The glass will round up at the
fusing temperature and give a number of completely rounded spheres
with a flat bottom.
Prevention
Thank you for the suggestion, I recently had a piece with many little bubbles that disturb the surface and detract from the intended purpose. One question - on the first flip, when you say to take to just below full fuse - do you have a bubble squeeze on that process? If so, how long? The blank is 2 solid layers, about 18" diameter. Thanks.
ReplyDeleteYou do not need a bubble squeeze, as the bubbles are already within the glass and there is no escape for them out of the glass other than by going so hot as to allow the bubbles to pop. This usually gives a poor result.
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