The
question is sometimes asked whether the rate of advance in a firing schedule should be
slowed when re-firing; for a fire polish for example.
Cynthia
Morgan contributes four circumstances where you would want to slow
the rate of advance:
“1)
On the previous firing you were fusing a whole bunch of little pieces
into a much thicker piece, so you need to reduce your ramp to avoid
thermal shocking the thicker glass
“2)
You think you might not have annealed the piece well enough on the
previous firing, so you're playing it safe
“3)
You suspect there's a crack somewhere in the piece (from cold working
or whatever) so you're reducing the chance it will expand quickly and
open the crack
“4)
You've got to do something to the glass/kiln at a certain point in
the firing cycle, and if you go at your normal rate you'll wind up
doing it at 3AM...so you slow down the firing and get more sleep.
“Otherwise,
well-annealed is well-annealed. If none of those four conditions
obtain, I don't see why you'd need to slow down”.
