Step 5: Feel the burn!!!

Picture of Feel the burn!!!
Why anneal glass?

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.
(see image)
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!
pbarnett6 years ago
I am looking to build a kiln to use for enameling metals. Wonder if an old and small toaster over would work. Basically following the same steps, laid on its back inside a suitable container so the elements are on the sides instead of top and bottom. If it had the Pyrex glass window I would be able to monitor the project. Since the firing time is pretty short and no annealing is required I should be able to do it. Any ideas?
I like that toaster idea if you build it (or already have) you should post it up here.

1 suggestion: I don't know the temperatures that you use for enameling metals but I would suggest that if you want to add a window to a kiln use fused quartz glass instead of borosilicate (pyrex) glass. Quartz glass has a much higher melting point and is the standard for high temp viewing windows. Good luck.
bonecholampworks (author)  glassguy236 years ago
Actually, I'd like to see that too, if it gets done! (that was the problem with the waffle iron - it works great, as long as you don't need to see inside it!) Yes, that's a great idea too, (I just didn't know it was called quartz glass!) I'm assuming you could buy this glass at a place that deals in wood stoves - as I'm also assuming that would be the type of glass in the front of my woodstove. (and, for certain, is has gotten hot enough in there to melt boro) Thanks for the tip! Janice
Old fashioned wood stoves used to use a mica sheet as a window. its thin and available from the same places.
bonecholampworks (author)  XTL5 years ago
Yep, we used to be able to get it, but I'm not certain anymore.
We heat with wood stoves, and the "Safetly Standards" stuff sure has changed over the last few years.  I'm not sure you're even allowed to use Mica anymore, too bad too, we have a georgeous antique corner stove, and I'd like to have an insert put in it to make it airtight, but I believe I'd still have to remove the mica, I'll have to check for sure.
Thanks for bringing that up!

Very cool idea. I do enameling, fusing and slumping and I wish this info had been available to me when I was getting started. Would have significantly cut my startup costs. I have four "real" kilns in different sizes now, but I may build one of these just for fun, or maybe to take to my kid's Cub Scout meetings to let the kids enamel some stuff.
I'm still amazed at how durable these little things are...
I did once kinda get 'distracted' and by the time I realized it, the coupler read
2000!  Once I peeled the melted glass off & fired it up again, it was fine.
(and when it's cold, you can tuck it under your arm & off you go)
Just keep the kiddies away - it does get really hot!
(might be able to roast a marshmallow or two if you're close enough!)
Good luck with the Scouts!

Thanks, I'll definitely put this one on my list. This sounds like an excellent starter enameling kiln (2K is way hotter than enameling requires), and it'll give the kids a chance to be creative and play with fire at the same time, without hosing up my Quick-fire kiln. Everybody wins!