Annealing Boro

[WhiteSnake]

Hello, I wanted to move into boro tubing but my Kiln is not big enough. Do I need/have to anneal boro tubing and if so, can I use a ceramic kiln for glass? Thank you

[wickedglass]

I'm assuming you mean after working it, because obviously you don't need to anneal before. It depends entirely on what you do with it. Complex forms should ideally be kiln annealed, but something like Christmas bubbles I never anneal. You can also flame anneal your work with a bushy flame ... run a working flame, then crank up the gas and anneal up where the flame is bushiest and get the glass hot to a point where it's just about to start glowing but not moving ... the idea is to get the glass to an even heat base.
Oh, don't believe what you hear (or read) about building up a layer of carbon to help flame anneal a piece, it's a complete myth (I normally use another word for "myth" ;) ).

[patienthand]

the layer of carbon doesnt help anneal the work.. but.. it does burn off at close to the anneal temp, so it is an indicator of the temperature of the work.

yes, you can anneal your work in a ceramics kiln, as long as you reach the annealing temperature. The glass has no idea its a ceramics kiln.. lololol

[wickedglass]

the layer of carbon doesnt help anneal the work.. but.. it does burn off at close to the anneal temp, so it is an indicator of the temperature of the work.

^ This is true, I should have been more concise and less general.
patienthand knows exactly what I was talking about, but neither of us spelled it out :lol: For those who don't, I was referring to the erroneous notion that the carbon layer helps to insulate the glass and allows it to cool down more slowly.

[WhiteSnake]

Thank you everyone

[WhiteSnake]

do you think this would suffice

http://fortmyers.craigslist.org/lee/art/2876523970.html

its a duncan

[Arcane Glass]

As long as that kiln can reach temps upwards of around 1200F you should be fine using that kiln. My ramp cycle on my kiln is something like, hold 2hrs at 1050, drop down to 960 and hold for 2 hours, ramp down to 660 and hold for 2 hours, then let it ramp down on its own to room temp. The ramp down between temps is about an hour long process in my kiln.

Here is a link to the annealing table from Northstar for Boro.
Northstar Users Manual (http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cts=1331330420571&ved=0CEUQFjAB&url=http%3A%2F%2Fwww.northstarglass.com%2FUsersMan ual.pdf&ei=b31aT5zKO6KPigKXrPGoCw&usg=AFQjCNHbxnRDdbDdmwMo5DqqnKjTm8EL-w)

[Jngljnke]

What do you mean when you say you have a ceramic kiln? Is the overall design catered to ceramic workers w/kiln tile interior, or is the interior made of ceramic fiber?

[menty666]

They're designed for ceramics

[wickedglass]

I'll let you in on a secret ... there is no real difference between a glass kiln and a ceramics kiln. I'm talking about brick lined kilns. I've never used ceramic fiber lined kilns for my glass, so I can't talk on that. Kiln fiber is nasty stuff and with all the other potentially dubious stuff already floating around in a glass studio, I stay away from adding more ;)
The only real differences are that ceramics kilns are able to go a lot higher than purpose made glass kilns, so you'll never have any issues with the kiln not being able to fire high enough to anneal glass and ceramics kilns don't have a bead/garage door, but if you have a front loader and you're handy with tools, you can even add one of those in short order.
Make sure you buy a kiln which has not been used for things like salt glazes or raku or something like that (which would be unusual for an electric kiln, but you never know). The low down is, buy a clean kiln which has no evidence of any deposits on the kiln bricks or the elements. If you can get your hands on a kiln which has only had bisque firings, such as a porcelain kiln (there are a surprising amount of porcelain doll makers out there), then jump on it, because they have generally been looked after very well.
I currently only use ceramics kilns, I bought them quite cheaply and have added digital kiln controllers to a couple of them. I have a proper fan forced (for even temp distribution) scientific annealing kiln, but because of the shape it's not particularly useful putting any sort of volume of glass into it. My small kiln is about 1 ft cubed, I use it as a garage and for my day to day stuff, the big kilns (the biggest one is about 3ft tall inside) are for my larger sculptural work.

The kiln below is one of our ceramics kilns we use for annealing and casting and is hooked up to a harco kiln controller. This is me with the kiln at 600C wearing my hi tech insulating suit ... the kiln was only used for firing decals onto tiles, so it's very clean and it was in almost new condition when we bought it. We also lucked out and it only cost us $500 to buy (not counting the $1800 it cost us to get 3 phase installed to run it(yes, holy shit))!!! ... the guy just wanted to get rid of it. The catalog price for this particular model (I looked it up at the manufacturer) is $12000 .... but now I'm dangerously close to bragging, so I'll sit back down :D

[wickedglass]

do you think this would suffice

http://fortmyers.craigslist.org/lee/art/2876523970.html

its a duncan

oh, in reference to that kiln, you should get a front loader. Top loaders can get really really uncomfortable when you have to put stuff in or take stuff out when it's at annealing temperature. Remember, you'll be leaning over it when doing that ...

[wickedglass]

also front loaders are easier to stack with shelves if you're making lots of smaller work

[Jngljnke]

I bought a new kiln that was billed as being "great for firing glass". I assumed ceramic fiber was what kiln tile was made from and bought it. When I opened the box I noticed that "do not fire glass on ceramic fiber" printed on just about every piece of paper in the box. Not exactly what I would describe a great for firing glass. I have to use terracotta tile on post to fire. Also, there is a quarter inch of slope from the back to the front. That is steep considering it is only eight inches deep.

[menty666]

I think they mean 'don't put the glass directly onto the ceramic fiber'. In other words, pick up some kiln furniture :)

Wicked... I know functionally they're the same, but I thought one of the key differences between glass and ceramic kilns is that the ceramic kilns tend not to have elements in the top of the kiln (the ceiling for front loaders, the lid for top loaders). With the clay it matters less about hot spots.

Also the ceramic kilns tend to go a bit higher temperature wise than the run of the mill annealers.

[WhiteSnake]

Thank you everyone for the help. This is great info

[Dragonharper]

I think they mean 'don't put the glass directly onto the ceramic fiber'. In other words, pick up some kiln furniture :)
...

Also when using a kiln for an annealer the temperature is no where near those used for fusing glass, which is what I would assume they mean by "firing" glass. I have a Paragon SC3, which is a fiber kiln, it came with a "shelf" that I place my hot work on. Also you can place a piece of fiber blanket on the bottom to protect it too. Don't ever use kiln wash on a fiber kiln, you will kill it.

[wickedglass]

Wicked... I know functionally they're the same, but I thought one of the key differences between glass and ceramic kilns is that the ceramic kilns tend not to have elements in the top of the kiln (the ceiling for front loaders, the lid for top loaders). With the clay it matters less about hot spots.

Yes, that also can be a difference, but you'll find that some ceramics kilns (coffin style kilns) often have elements in the top as well. You'll also find that for annealing boro, it doesn't really make any difference having elements in the ceiling, especially considering that heat rises and will gravitate to the top of the kiln anyway. But again, with the size of kiln most people use, it's not an issue. Although, top elements come in useful when you are slumping sheets of flat glass which need to be heated gradually from room temp to slumping temp. The kiln I'm working in up there ^ doesn't have top elements and we use it for casting solid objects, sometimes up to 25kg to 30kg and we anneal those slowly for over a week with no problems.
To really avoid hotspots a fan forced kiln will do the trick, these look like elongated horizontal barrels (reminiscent of a glory hole) and have no corners which can trap heat. The whole back is a mesh that the fan blows through and the front has interior holes which recirculate the hot air, through the inside skin, back to the fan. Other than that you will find that there are temperature variances inside of kilns, no matter if there are ceiling elements or floor elements ... especially when those elements click on.

[deb tarry]

Good info Wicked and I like your high tec suit. :)

[patienthand]

that high tech suit reminds me of my furnace glass days. I would put pot holders in my bra to protect the girls.. those few extra inches gals stick out can be really really painful.. you also learn fast not to wear t shirts with decals on the front

[deb tarry]

Ha ha pot holders your killing me. Someone help me off the floor, I fell off my chair laughing. :)

[Jngljnke]

The "high tech" suit makes Eye of the Tiger go through my head. Not sure why, but that and other Rocky references are all I can think of when I look at the picture. In my head Wicked is Stalone, despite looking like he's in a scene from Fear and Loathing in his profile pic. Maybe I should lay off the movies.