It is
the monitoring and observation of the effects firings as they progress that allows confidence in
setting firing temperatures and schedules. Although we all have busy
lives, planning the firings so you can watch at the forming
temperatures enables you to develop your firing practice much more
rapidly than firing and waiting to see what comes out the next day.
It means that in a single firing you can pretty accurately determine
the temperature you need for firing that type of piece, rather than
an number of separate firings.
You
set your schedule - for the best guess that you can make - at the
required temperature, rate of advance, and soak to achieve what you
need. At about 50ºC to 20ºC (depending on your certainty) before
the set point, you begin peeking to see what the glass is doing.
When the glass has achieved the desired result, you advance to the
next segment. You of course, have already refreshed your memory on
how to do that from your kiln manual.
There
is a method of opening and closing kiln to be safe and avoid
disturbing the contents. Any observation ports should be opened
first. The lid/door should be opened slowly and only enough to see
what you had already planned to look at, to determine whether it is
ok or a decision is needed for some other action. This opening should
be only a few seconds. The air temperature will change dramatically,
but the glass temperature will lag behind significantly, so a few
seconds with the door only cracked open will not damage the glass at
most temperatures. The exception to this is the annealing range –
generally around 520C to 400C. The kiln should not be opened at these
temperatures so that there is no disturbance possible to the steady
and even annealing of the glass.
At
temperatures above the annealing, you need to have protective
clothing. At the minimum you need natural fibres such as cotton or
wool, and eye protection. It is important to check with your hand
the amount of heat coming from an observation port before moving your
face toward it to look into the kiln. When the kiln is being opened
even for brief periods, you should protect you eyes from the infra
red given off by the kiln's interior. You should have something to
protect your arms and chest too.
Always
when raising and lowering the lid – or opening and closing the door
– do it slowly to avoid creating puffs or billows of air moving
through the kiln which might disturb the pieces at low temperatures
or move debris over the hot glass at the higher end of kiln forming.
If the
glass has not achieved what you want by the end of your soak, just
extend the hold until the effect is achieved. You will have reviewed
how to do that from your kiln manual before starting the firing.
When the glass has achieved the effect you desire, advance to the
next segment of the schedule as the kiln manual directs.
You
then record the schedule including temperatures, rates, times,
effects, etc. You should include a description of the project and
its dimensions and nature e.g. full fused, tack fused etc. You will
also want to include what this was fired on, what kind of mould –
include its description. This will give you the reference for that
nature of project for the future without needing to guess.
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