Hot Box, anyone?

[JulieV]

Just curious; anyone use the Evenheat little Hotbox kiln for batch annealing? It's going to be my first kiln (cuz it's so quick and easy for slumping) and I wondered if anyone else uses it too .

[BillBrach]

It cools WAY TOO QUICKLY to anneal beads UNLESS you add a stand-alone digital control ($200 and up).

It also cools too quickly except for anything but really small pieces of glass if fusing.

To properly anneal glass, it needs to cool NO MORE THAN 2 degrees a minute. You can test your kilns cooling rate by taking it to say a 1000 degrees, turning it off, and timing how long it takes to get to 800 degrees.

To properly anneal glass, this time would need to be about 100 minutes. I KNOW the Hotbox won't do this 'cause I got one of those little beasts. It is a great kiln to travel with though, because it is small and lightweight. I added a homemade digital controller to mine to accomplish the task as an annealer.

[JulieV]

Gosh! I know you need to babysit it a lot through the anneal cycle. I have used one it at the stained glass shop in town for my batch annealing and I know lots of other folks that are have great success with it. You're worrying me!

[BillBrach]

Julie,

If you are not selling your beads, but simply consuming them yourself, then no worry. Who cares if one cracks months later if it is yours.

But, if you are selling your beads then you need to do a little research on the proper annealing of beads. Just because your beads aren't cracked when you take the lid off after it is cooled, does NOT mean they are annealed !!

Bill

[JulieV]

Originally Posted by BillBrach

Julie,

If you are not selling your beads, but simply consuming them yourself, then no worry. Who cares if one cracks months later if it is yours.

But, if you are selling your beads then you need to do a little research on the proper annealing of beads. Just because your beads aren't cracked when you take the lid off after it is cooled, does NOT mean they are annealed !!

Bill

Bill
I actually did do more than a little research before I decided on the hotbox kiln. And I believe you are wrong when you say you cannot anneal in it.

Here's just a little of what I had found:

"This handy little kiln is a "gotta have" for any studio, be it personal or business. Compatibility testing, color tests, small design elements, jewelry, seminars, you name it. It can even anneal. The Hot Box is a handy table top kiln, perfect for fusing jewelry, small slumping projects, compatibility testing, color tests, seminars, and annealing. Unique construction helps you maximize the kiln's space: entire kiln lifts up like a collar, so you don't have to reach into the kiln to place items on fusing surface (an indispensable feature for making fused bracelets). Its rugged construction and ease of use make it very user friendly. Has a manually controlled infinite switch and pyrometer. Operates on 120 V, 12 amps. Includes 90 day manufacturer warranty. Inside dimensions: 6-1/2" x 6-1/2" x 4" deep."

And some testimonials from people who use it for annealing:

"I do batch annealing and fuse small items. The best thing I like is the window in the top and fast heating. It only has an "infinite switch" so I do have to "kiln sit" all morning, but I plan for that. Also very portable. This is my first kiln and I like it."

"I use an Evenheat HotBox - and I batch anneal. I think it's perfect for the $$ - if I had more $$ I'd trade it in for something a little larger with a digital controller, but I don't .... so I can't ..... LOL!! I can see me using this kiln for a long time yet!"

"I have the Hot Box and I use it every night and have it going while I am making beads. I put two kiln 1x7 pieces in it, use two fire bricks over the top of the opening, and stand my mandrels up for annealing after the beads are made. I can fit 30 or more beads in it this way."

So I guess everyone's entitled to their own opinion and I do appreciate hearing yours. Thank you.

[MikeAurelius]

Any kiln can be an annealer.

There are many different ways to anneal glass.

Will a digital controller make it easier? Yes. You can set it and walk away. Is it the ONLY way to anneal? NO.

With an infinite controller, if you have patience, you can anneal beads.

You simply have to follow the temperature curve for annealing.

It will take several practice runs with an empty kiln to find the proper settings and time, but it can be done.

To say otherwise, is just, plain, wrong, in my opinion.

[JulieV]

Thank you Mike. I too was under the impression you could anneal in any kiln - with practice and patience. And definately a few "dry runs" to get the schedule down pat.

[starlia]

I actually had a hot box before I purchased my bigger kiln with controller. Yes I batch annealed in it but I also garaged my beads in the thing while I worked. Yes it's a pain to babysit the controller but it was affordable and did the job. I was then able to purchase my much larger kiln with controller after I had enough annealed beads sold to pay for the contraption.

[JulieV]

Thanks for sharing that with me, Starlia. Quite a few people I know use it too; no, it's not the "perfect" kiln for annealing, but I've been told it does the job! I also want to do a lot of slumping and some small fusing. Think I'm gonna enjoy just having a kiln, even if I have to watch it alot. But now with the window in the top, that could also turn out to be fun!

[starlia]

I loved my little hot box. Now I wish I hadn't sold it because my bigger kiln takes up so much room. I started out fusing and slumping and then lampworking. It's great for both applications.

[UCBYCINDY]

Hi Julie,

I am not sure of the type of kiln you are buying, but I know for a good price and if you know any one handy you can get one made for under $200 canadian. I bought a digital controller from out east, and I am waiting my brother to assemble it for me...it will be so nice to have one.

Cindy

[JulieV]

Hey Cindy~
You mean get a WHOLE kiln made for under $200????????????????

Originally Posted by UCBYCINDY

Hi Julie,

I am not sure of the type of kiln you are buying, but I know for a good price and if you know any one handy you can get one made for under $200 canadian. I bought a digital controller from out east, and I am waiting my brother to assemble it for me...it will be so nice to have one.

Cindy

[BillBrach]

The $200 Cindy was referring to was for a digital controller, and NOT a kiln with digital controller.

A really LARGE kiln, like ceramics kilns with LOTS of fire brick, MIGHT cool at the right rate to anneal beads. It would have to be tested to see that is does not cool faster than 2 degrees per minute from 1000 to 800 degrees.

Technically it is POSSIBLE to use a non-digital controlled kiln as an annealer.
Realistically, it isn't because NOBODY is going to sit next to it and turn down the infinite switch a very tiny amount every two minutes for an hour and a half.

The other problem you have is that the pyrometer meter on your Hotbox is very inaccurate. At a 1000 degress indicated on that little white dial, my Hotbox was 75 degrees OFF of the actual temp, using a professional temperature meter. I modified mine by adding a fire brick top to the unit, to allow me to easily insert a bead still on a mandrel, into the kiln.

I will repeat what I said, then I'm NOT commenting again on this thread. You CANNOT properly anneal beads in a kiln WITHOUT a digital controller.

[JulieV]

Thanks Bill. As soon as I posted, the uh-duh light went on!

[snootyvixen]

Originally Posted by BillBrach

Realistically, it isn't because NOBODY is going to sit next to it and turn down the infinite switch a very tiny amount every two minutes for an hour and a half.

I have a HotBox - love the lil bugger! I sit next to it and turn the infinite switch a very tiny amount every two minutes while I'm making and eating dinner.

Nobody

[MikeAurelius]

You do not need a digital controller to anneal beads. Period.

Digital controllers are nice and easy to use. But digital controllers have only been around for the artist for the last 10 or so years. Before that, what did they do?

They used the infiinite switch on the kiln. Or they got the temp on the kiln to the annealing point, then turned it off. Or they used a kiln sitter with cones.

Beads are very small items. We are not dealing with huge pieces of plate glass or telescope mirrors.

It isn't rocket science, and if the temp is slightly off, chances are the bead is going to anneal anyway. The annealing temperature is a RANGE, based on time and temperature and cross section of the piece to be annealed.

This same issue keeps coming up time after time, and each time it gets debunked. It seems that the only people who have a stake in demanding that artists use digital controllers are those who sell them.

[BillBrach]

Let me make it perfectly clear, I DO NOT SELL DIGITAL CONTROLLERS, so have NOTHING to gain with respect to the digital controller issue in this thread.

On the other hand, I know that Mr. Aurelius does sell them through his AuraLens web site. In fact, if you were to buy one, I'd recommend that you buy it from AuraLens.

And Mr. Aurelius, you pose a great question about what bead artists did 10 years.

* Back then, there were only a handful of bead artists, who certainly did not understand the concept of annealing. It wasn't until 1985 or so, that even the concept of COE was starting to be understood amongst glass artists. Granted, the plate glass and glass container industries certainly knew about the concept of annealing long ago, but that was not common knowledge among bead makers. What was commonly done back then was flame annealing, which is an art in itself, and is not a simple thing to do properly. Today, flame annealing for the average bead maker is just not reliable enough when you consider the many digitally controlled bead annealers under $500.

* Back then, the few artists that DID anneal their beads in kilns, were using LARGE ceramics kilns, which are designed to cool slowly in the first place.

* Back then, the physics of the strength of a spherical object, was minimizing the problems because of the lack of annealing.

Additionally, Mr. Aurelius, you forget that were are talking about an Evenheat Hotbox, that if brought to 1000 degrees and turned off, will be at almost room temp in an hour or so !! I actually LIKE that fact that the Hotbox heats and cools quickly, as it allows me more "throughput" (work output) than a kiln that retains a lot of heat.

If all of the kiln manufacturers would build kilns with sufficient thermal mass to cool naturally at the correct rate, then we would NOT need digital controllers on bead annealers. It isn't feasible to do this, because it makes for a large, heavy, expensive to build, expensive to ship kiln. And, a kiln with a digital controller can be used for WAY MORE than just a bead annealer, whereas a kiln built with the thermal curve for a proper bead annealer, will almost always have to be used as a bead annealer.

My Hotbox, BECAUSE of the digital controller, is the most used kiln we have. I anneal soft glass in it, I anneal hard glass in it, I slump in it, and I fuse in it, and I roast peanuts in it (just kidding). It would not be this versatile without a digital controller.

Let me repeat myself, I am in agreement with Mr. Aurelius. Yes, you can anneal in a large kiln of sufficient thermal mass, yes, you can anneal in almost any kiln with an infinite switch: if you CALIBRATE the pyrometer, if you are WILLING to LEARN its THERMAL BEHAVIOR, and if you are willing to BABYSIT it for 90 minutes or more. If not, use a digital controller to make your life easier.

[MikeAurelius]

Then I suggest, Mr. Brachhold, that you edit your statement from above:

You CANNOT properly anneal beads in a kiln WITHOUT a digital controller.

It is absolutes like this statement that get people into trouble.

You also overlook the fact that beadmaking has been going on for thousands of years, and it has been only the 50 years or so when annealing was even done, and even then, rarely.

I held in my hands a year or so ago trade beads made in England around 1700 or so. Were those annealed? Hell no.

So, let's get off our high horses about annealing and technology, ok?
Oh, and thanks for the plug. I appreciate it.

[snootyvixen]

I have a question, and believe me, I'm not trying to stir the pot ...

My Hotbox hits 940 - 950 on setting #2 - I anneal my beads for an hour at that setting. When I turn it down to #1 (which will give me 570 - I hold it there for about an hour, or even overnight if it's taking too long to get there!), it takes a good 3 hours to get down to that temp. Do I have a defective kiln, seeing that Bill's cools to room temperature in an hour?

Vikki

[Mr. Smiley]

Originally Posted by snootyvixen

I have a question, and believe me, I'm not trying to stir the pot ...

My Hotbox hits 940 - 950 on setting #2 - I anneal my beads for an hour at that setting. When I turn it down to #1 (which will give me 570 - I hold it there for about an hour, or even overnight if it's taking too long to get there!), it takes a good 3 hours to get down to that temp. Do I have a defective kiln, seeing that Bill's cools to room temperature in an hour?

Vikki

Hey there Vikki. Holding at 570 doesn't really do anything for the glass. If you want to hold it at a temp or pause on the way down, just above the strain point is a good place (850-860 for soft glass). All that does is allow everything to catch up (internal temp of the bead) before you dip below the point where stress is locked in. On small stuff, you can do it, or not do it. The really important part is going from annealing temp to strain point slow. If it is done slow enough, you will not introdue new stress into the glass. I mean, you just soaked them to get rid of it, why put it back, by rushing on the way down.

What most people don't realize about annealing is this:

You are not cooking the glass. You are holding it at a temp high enough for the glass to relax on a molecular level. Once it is relaxed, you need to cool it slowly, so the external temp is not drastically different than the internal temp. If the ouside layer of glass is cooler than the interal temp (or vise versa), there will be stress from one pulling on the other. Annealing is simply cooling slow enough to keep the stress from building back up in the glass. If you do this above the strain point, you will have annealed beads. Any stress introduced below the strain point is temporary if it doesn't thermal shock your piece.


I run a really conservative annealing cycle. You can't really go too slow on the way down. There comes a point when it's a waste of power, but it won't hurt a thing... now going too fast can cause real issues with the strength of your finished work.

I hope this helps a little. I tried not to get too technical.

[BillBrach]

Vikki,

Great to see you over here on LE

940-950 is a little too low for the anneal hold temp. Try bumping up very slightly above your #2 setting, and try to find the point that it holds 970. Also, try to find a setting below #2 that holds the temp at about 850. This is about the best you will do with the infinite control.

Also, be aware on my Hotbox that the little temp dial on the unit was off about 75 degrees at 1000. I don't remember which way I adjusted it, but made it match a digital thermometer meter that I have, which had an almost new thermocouple sitting next to the one that came with the Hotbox. So, if you ever get a chance to calibrate yours, I'd advise it.

EDIT: What tipped me off was when the kiln was at room temp (sitting for several days unused), the little dial was indicating 100 degrees when the air temp was below 70. This sent me off on the cross check. This is easy for you Hotbox owners to do, simply leave the lid off overnight, and put a known good thermometer, such as a meat or candy thermometer next to the kiln, and compare the dial vs. your kitchen thermometer in the morning.

I'll check the exact temp drop rate on my Hotbox sometime soon and post back. Right now, it is still packed from my last lampworking roadtrip. I just love my Hotbox, I can easily put the kiln and the external digital controller in a cardboard box and still carry it...LOL

Bill

[Mr. Smiley]

Good point Bill. Most kilns are not all that accurate out of the box. Escpecially the cheaper models. Contact the maufacturer for info on how to calibrate them. The thermocouples will also derade over time... it's good to check them at least once a year or so... more often if you use them alot. I do boro work, so I have color changes that happen in a certain range to judge mine by continually. My front loading kiln is off by almost 100 degrees at 1000... so it's not uncommon for them to be wrong. Mine shows lower than it really is, so if you went by the digital readout, you would be over cooking them by quite a bit.

[UCBYCINDY]

Hi Julie

You asked if I was going to have my whole kiln made for under $200. Yes I will, Bill was kind enough to answer for me but actually my controler cost me $100 us...I then purchased a tool box for $20 canadian. My brother has the insulation already (but I am sure it isn't to expensive) and used stove top burners. As you can see it is actually less than $200...but you need someone who can construct it for you. I am lucky...thanks goodness.

It will be so nice to have my own

[BillBrach]

Cindy,

I'm sorry for mis-speaking in your behalf on the $200 !! Thats a great deal. I've got 6 of those little Fuji controllers, and plan on building all kinds of things. Next project is a small benchtop annealer, once I have my "sea legs" back !!

I'm also looking into a commercial digital controller package too, hopefully, I'll be able to sell it for around $200.

Bill

[JulieV]

Snootyvixen aka Nobody (btw, that was funny!!!)....Thanks for the tip. I plan on working on other projects while bablysitting the kiln.....don't think it'll be too much of an inconvenience. Also get caught up on some of my mosaic and stained glass projects that I've been neglecting since lampworking took over my life!

Mike, with all the research I've done, I've come to the conclusion that annealing temps. are in fact "ranges" allowing for some variation of degrees. Thank god!!

Bill, when I read this - "You CANNOT properly anneal beads in a kiln WITHOUT a digital controller", I really thought I had made a huge mistake in my purchase of the hotbox. But then I gave my head a shake and realized it was just your opinion; of which everyone is entitled to.........but you did scare the sh** out me for a second or two!!! That's a great idea regarding comparing the temp. with a kitchen thermometer.

Cindy - REALLY???!!!! That's fantastic. $200.00 Canadian and you've got yourself a kiln. Very awesome.

Brent, thank you also for the tips. This little thread has taught me quite a bit.

[Lyssa]

Originally Posted by BillBrach

Technically it is POSSIBLE to use a non-digital controlled kiln as an annealer.
Realistically, it isn't because NOBODY is going to sit next to it and turn down the infinite switch a very tiny amount every two minutes for an hour and a half.

Dredging up an old argument...

My husband sits - with a clipboard and a stop watch - next to my GAS kiln with NO controller for 6+ hours every time I want to batch anneal, because he loves me. My beads are annealed perfectly (proven by looking at the clear ones through a polariscope).

I guess I'm just lucky.

[PiP]

My EvenHeat Studio 8 has worked perfectly for me for batch annealing. I've recently upgraded to their Fishbone. I love Evenheat.