As a lampworker/glassworker, I needed an annealing kiln that was more portable than my huge Paragon kiln, for travel & show work.
Here's my quick, easy & economical alternative.
This is my first instructable - so please bear with!
PLEASE NOTE: SOME OF THE STEPS INVOLVED CAN BE DANGEROUS!!!
READ THROUGH ENTIRE PROCESS FIRST AND FOLLOW DIRECTIONS CAREFULLY!
POTENTIAL ELECTROCUTION HAZARD!
PLEASE BE SAFE, VENTILATE WELL, POTENTIAL FOR HAZARDOUS FUMES!
POTENTIAL FIRE HAZARD - KEEP A FIRE EXTINGUISHER RATED
FOR ELECTRIC FIRES HANDY!
-An older style steel electric waffle maker with removeable waffle plates.
Pretty doesn't matter, functionality does - see image.
I see them for sale regularly at yard sales & 2nd hand shops for a couple of bucks.
(I've seen newer styles that seem to be a light aluminum, no experience with these)
(Our particular thermometer is a 'flue' thermometer, meant for use inside
a chimney. They're available in a range of temperatures - for our use, we need one that
can read up to 1500F. Available at wood stove resellers, or possibly ordered from an appliance supplier - Cost? Approx: $30.00)
-Insulated container of some sort to house the waffle iron.
(old metal refridgerator drawer, small propane barbeques, less the inner parts,
work great too.)
-Agregate, or other insulating material.
-Insulated/Fireproof fibre matting.
(may be purchased at some welding shops & most hot glass facilities/shops)
Optional/fire brick - kiln liner brick.
(Kiln liner brick is exactly the same as stove liner brick, however, stove brick is
a fraction of the cost and can be easily purchased anywhere wood stoves & said
accessories are sold)
Tin foil. The heavier guage, the better.
Can of spray brake cleaner.
Step 1: Cleaning & Prepping the Waffle Kiln
Remove any plastic or bakelite type handles, feet, or other 'accessories'.
(keep in mind, my mini kiln has successfully ramped up to 2000F - these handy
plastic handles & feet will melt like candy if not removed - I'm pretty sure they'll smell bad too!)
Remove waffle plates.
You are now faced with an shell of a waffle iron, complete with elements, wiring,
ceramic posts that hold the elements, and some whatnot gagetry.
It's probably really greasy & dirty in there - any grease or carbon fumes/smoke emitted
during your anneal process could leave smudges & imprints on your glass projects.
(not to mention a heck of a smell, probably...I'm not big into nasty smells...)
Take the iron outside & shake any loose gunk out.
Wipe any excess you can reach with paper towels.
Key words here...SAFETY & VENTILATION!!!
Take the iron outdoors & place it on the ground or on some other heat proof surface.
Place it somewhere away from highly flammable objects.
Spray the insides liberally with brake cleaner. (don't inhale the fumes - brake cleaner is nasty!)
Spray the inner wiring & coils, anywhere grease may have collected.
Try to avoid letting the brake cleaner run out onto any outer wiring - if so, wipe it off.
Let it sit for five minutes & then plug it in & fire it up.
Be ready...this will be messy, smoky & potentially scary!
Keep your fire extinguisher handy, just in case.
(be aware of local fire bylaws, perhaps your neighbours don't have THAT great a sense of humor...)
As the iron heats up, it will begin to smoke. Alot. Even more. Still more!
It may even catch fire - although this should last only a minute or two at most.
(here's where the fire extinguisher comes in handy, just in case...)
Keep an eye on the outer case of the iron - it probably won't get too hot, but you'll need to
I didn't find it was necessary - but can't hurt to think ahead!
I simply pulled the cord directly away from the iron before I plugged it in, so it wasn't
lying right next to it & covered it with the foil to sheild it from any direct flame.
Once the whole mess has stopped smoking, unplug it & let it cool down.
A power bar is handy for this step, as, if a problem occurs, the power bar
should cut power, or, you can quickly hit the switch before unplugging the power
bar & not have to worry about having to touch potentially hot electric cords...
Step 2: Cleaned & Ready!
The kiln shown pictured was already built, and I didn't feel the need to disassemble it - so I've just zoomed in on any important parts.
There's a similar kiln kit available commercially that is made out of a small toolbox.
(red style, steel toolbox with hinged lid & one inner tray) This kiln is pretty much the
same design, less the fancy digital controller.
Your waffle iron may differ someone, and some small adaptations may be in order.
This particular "kiln" has been in and out of annealing service for about 8 years now.
Now that it's all cleaned up & cooled off, look inside...
As shown in the pic, the insulated wirings & elements should be
nice & clean, white even, if the wiring is coated with a fireproof outer shell.
(please excuse the dusty mess in the bottom, this is the galvanized wire coating,
I just hadn't swept it out yet)
This iron had many, (many, many) years of use as a waffle maker before
being relegated to glasswork, yet the brake cleaner job cleaned the inner workings as though
they were new.
Once again, I mention, this kiln has been ramped up to 2000F - yet still the insulated wiring & exposed elements continue to function...who knew?
Step 3: The Build!
DANGER - ELECTROCUTION HAZARD
Now that the elements are now exposed, they pose a potential burn/electrocution hazard,
and must be sheilded for protection.
I purchased regular galvanized grid wire (as shown in image)- 1cm x 1cm, cut it to size,and fit thepiece into both the top and bottom of the iron, wiring them into place so they don't fall in or out.
Be sure to trim your gridwire so it doesn't come into contact with ANY wiring or elements.
(results could be shocking!!!) Tuck any loose ends in and nip them off.
The gridwire most commonly available is galvanized - after a couple of firings, the galvanized
coating on the gridwire will flake off. (as seen in step 2 image)
Sweep or vacuum it out now and then, and if your gridwire becomes weak, replace & repeat.
If you can find it ungalvanized, even better.
In some cases, the ceramic posts already inside support the grid wire too.
Make a snake out of tin foil long enough to go around the outside edge of the bottom of the iron.
(most irons are on a hinge, the foil fills the gap that the original waffle presses filled,
and stops heat from escaping.)
Press the foil down onto the bottom, close the top & press it down too, making an imprint...
Kind of like a gasket...
Repeat with the top.
I wired my foil down, as after a few uses, it would sometimes separate when
I lifted the lid.
You'll need to experiment to see what works best for you.
This particular iron had some holes already punched out for another handle which I removed.
These holes were perfect for inserting the temperature probe. Yours may not have such holes,
and so,you may have to punch/drill a hole in a more applicable spot, or,
you can insert the probe thermometer somewhere between the top & bottom, wedged between the foil.
(try to keep it away from the elements as much as possible,or you'll get a higher reading than normal.)
The probe also should not be touching any wiring or elements or electric shock may occur!
Place the probe in a location where you'll be able to read it easily.
(remember, it'll be hot, so put it somewhere you can see it & possibly reach to shift it,
Step 4: Insulating!
As for the main kiln build, that's about it...however...
Because this setup has little or no insulation, it loses heat at a rapid rate.
(uneconomical & a pain in the behind!)
As a result, I chose to insulate it.
I used a metal refridgerator drawer to house my kiln - dropping the iron into the bottom, then
filling any gaps up to the bottom lip with aggregate.
The back cord (as seen in image) is wrapped in insulation & foil, sunk down into the insulating aggregate, & clipped to the edge to keep it from falling back in next to the metal & melting.
Check the cord frequently to be certain it's not damaged or melted, or frayed in any way.
If you happen to be handy electrically, or know an electrician, it may be necessary to replace
this cord with one that can withstand a higher temperate.
I used a small section of sheet metal for a lid, and covered it with stove liner fire bricks, also
called kiln liner bricks, (at a much higher price...)
There's no pic of the lid - I couldn't find it at this time...:/
Fireproof insulated fibre matting works well as a lid too, however, it falls apart after a short
amount of time, so, I found the bricks far more economical.
I can also easily lift the lid to take a peek at the temperature probe this way.
I was quite surprised to find that these odd probe thermometers are actually quite accurate.
(stuck one in my paragon kiln one day, just because I wanted to know for sure...!)
Step 5: 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.
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!