Step 5: Feel the burn!!!
A quote from Bandhu Scott Dunham - a famous Hot Glass Master...
"The basic principle of annealing is to hold the hot glass at a temperature where it is fluid enough for internal stresses to relax, and then to cool the glass so slowly that both the inside and the outside, the thick sections and the thin sections, have a chance to shrink evenly. This way, no stresses are developed or 'frozen' into the finished piece."
Soft glass - most commonly known as moretti - has a fluid temperature of approximately 1770F. (again, I repeat - this kiln ramped up to 2000 degrees in a test run - 2000F will seriouly melt any soft glass you may be using & cause it to drip onto your elements, hence, ruining your kiln. Realistically, very little should ever touch your elements. If something drips, turn everything off, unplug, cool slowly, then clean it off!)
If you're into slumping glass, this is wonderful, however, if you're annealing beads, this isn't a good thing!
Hard glass, commonly known as borosilicate, or, pyrex, is a much harder glass, not recommended or tried in this small kiln.
To anneal beads, make a couple of supports with extra grid wire to support bead mandrels.
This keeps the beads from touching any grid wire & possibly getting marked up.
It also supports the bead mandrels & prevents them from falling into the kiln &
coming into contact with the exposed elements and any exposed wiring - should
one of your mandrels or any tool fall into the kiln & contact the wiring, unplug it
before removing, or you could be in for a nasty shock.
I simply folded a section of grid wire in half, sort of in a tent like shape & placed it
inside the kiln.
Two pieces folded this way easily support a number of bead mandrels.
To slump, use a small piece of kiln washed kiln brick to place your glass on.
(don't forget, the glass will stick to the brick without some kind of coating - kiln wash is
cheap and can be purchased at any hot glass or ceramic supplier, or kiln manufacturer)
The tricky part of these 'do it yourself' kilns is the annealing process...
I'll use annealing soft glass beads as an example.
Soft glass, (moretti) with a COE of 104 needs an annealing schedule of:
Approximately 1 hour at 960F.
Temperature down, 100 degrees per hour to 800F for another hour.
Temperature down, 100 degrees per hour to room temperature.
With a modern kiln, the process of slowly cooling down or ramping up is
usually done with a computer controller.
Our wee waffle iron, however, has no controller.
Heat regulation is done by powering on and off, and, once you've settled into
a routine, a timer is helpful.
You'll have to monitor your first few firings closely to be certain your temperature
isn't getting too high, and your probe is fairly accurate.
(if your beads begin to droop & melt off the mandrel, it's too hot!)
Also, I found with the insulation packed in well, simply turning the kiln off
after the 800F hour, refaining from 'peeking' & keeping the heat it, the kiln lost heat at less than the required rate of 100 degrees per hour...
Once again, I stress SAFETY in all aspects - don't forget to VENTILATE!!!
(should you be indoors, which, I reiterate, is not a good idea...garage, maybe ok...with a fan)
Keep a fire extinguisher handy.
I personally use a power bar, at all times, during an anneal with this kiln.
If there's a problem, I can disconnect while being fairly far away from the danger zone.
Lead glass in itself produces fumes of an unwanted nature, I can't even begin to imagine how bad a lungful of galvanization would be!!!
I strongly suggest this "DIY" kiln only be operated out of doors.
Always open to new adaptations of my waffle kiln!
Thanks for looking!