Dichoric & iridized - WarmGlass.com

Dichoric & iridized

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cindabr
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Dichoric & iridized

Postby cindabr » Tue Jun 24, 2003 4:50 pm

:? Could someone tell me the difference between dichroic glass and iridized glass? I have tons of stained glass that is iridized. I'd like to use it for slumping.

Can iridized glass be slumped without burning off the iridized coloring? If so, does the iridized coating go face up or face down?
Thanks

Cinda

Kitty
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Postby Kitty » Tue Jun 24, 2003 5:07 pm

iridized glass has been sprayed with a chemical (stannous chloride i believe) at high temp, and it leaves the coloration. dichroic glass is coated in a vacuum chamber at much lower temps, totally different process, and the colors come from different vaporized metals plus quartz.

both of these glasses can be slumped, either side up. some people make bowls with iridized undersides, which are quite deluxe because of that beautiful bottom.

if it's stained glass, you'll have to check on compatibility if you intend to mix up the different colors you've got. if you've got big sheets of the stuff, you can fuse pieces cut from the same sheet to themselves without a problem. so, you could make a one-color slumped bowl with an iridized surface if you fused two pieces cut from the same sheet together, and then slumped it. you might need 2 sheets fused together to get the minimum 1/4" thickness that works best. good luck with your experiments.

Cynthia

Re: Dichoric & iridized

Postby Cynthia » Tue Jun 24, 2003 5:24 pm

cindabr wrote::? Could someone tell me the difference between dichroic glass and iridized glass? I have tons of stained glass that is iridized. I'd like to use it for slumping.

Can iridized glass be slumped without burning off the iridized coloring? If so, does the iridized coating go face up or face down?
Thanks

Cinda



One other difference between dichro and irid is that dichro will shift from one color to another in reflected light. di=2, and chro, like chromatic=color.

Art glasses arent intended to be fired, so often the irids will burn off at fusing temps. Irid up or down is up to your preference of having it inside our out of the form.

At bending temps you may have success with the irid surviving. Art glasses don't necessarily have the same coe as fusible glasses either so I would ramp down through 1000 to 700 at 150 dph and see what that gets you for annealing. Also, to bend, I would watch it and hold at the temp that you see the glass begin to bend at...keeping your upper temp as low as possible.

Bob
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Postby Bob » Tue Jun 24, 2003 5:35 pm

Hi Cinda,

The iridized coating on glass is actually a thin coating of metal. The coating on glass made for fusing won't burn off at the temperatures used for kilnforming glass. The coatings on glass made for stained glass can (and do) burn off at temperatures as low as slumping temperatures. These stained glass coatings were not intended for fusing.

For me the two consequences of using iridized stained glass in the kiln are:
1) the coating may burn off leaving a patchy effect. This is not controllable (to my knowledge) so you never know what you are going to get.

2) if the coatings are burning off this may present a health hazard. I would try to find out what elements/metals are used to create the coating before I started volatilizing it in the kiln. Maybe I'm paranoid (well actually I am) but this may present a health hazard. Does anyone out there know what chemicals are used to iridize glass for stained glass applications? Does the burn-off represent a risk?

Another problem of working with glass intended for stained glass is that it can change a lot when fired. Textures such as ring mottles and cat's paws tend to disappear. Colours might strike from one colour to another (particularly the reds). The glasses haven't been formulated to minimize devitrification. Oh yes and then there is that old compatiblity problem.

So I would do some research on the coatings, and lots of test strips to make sure that the glass will actually work for you.

Hope this helps.

Cheers,

Bob

Kitty
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Postby Kitty » Tue Jun 24, 2003 5:38 pm

hey bob, that's interesting about the iridized coatings not being the same on fusible glass as on stained glass. never knew there was a difference -- just assumed they were made the same way. don't have any occasion to mess with stained glass, but it's interesting to learn something like this. thanks! kitty.

Bob
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Postby Bob » Tue Jun 24, 2003 5:46 pm

Hi Kitty,

I don't really know much about iridized glass other than that I have seen mottled or patchy coatings on glasses that were not made for fusing. I may be totalled incorrecty on the health hazard issue, and would really welcome comments from anybody that has real knowledge about irid coatings. Until then I would play it safe. I'm not only paranoid, I'm also conservative.

Cheers,

Bob

Kitty
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Postby Kitty » Tue Jun 24, 2003 6:06 pm

caution works for me, too. the only stained glass project i fused was with a piece of ring mottle, and the rings did fade, the sheet darkened up somewhat and wasn't as fab as it was before i heated. it did make a very nice plate, i must say, but not what i planned. i wont try it again.

it's tempting to try to figure out how to use any and all scrap glass, so i can identify with someone wanting to figure out how to use stained glass if they happen to have a bunch of it. i've been making small dishes from the remnants of big plate projects. i have one store that buys all of them from me, so they have a nice selection and i don't have to look around for another outlet. i like the price i get, it keeps the studio from getting clogged up with left-overs, and the $$ buys more supplies.

Lynne Chappell
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Postby Lynne Chappell » Wed Jun 25, 2003 1:27 am

Well, this getting older is a drag. I'm sure I knew what Spectrum used to iridize their glass but it just won't come to me. I know it's not as dangerous as the stannous chloride, but it never occurred to me that it might be a hazard when it burns off in the kiln.

I've had good luck with the iridized coating on Spectrum's stained glass up to about 1375F (just high enough for a minimum tack fuse). If the coating is on the bottom it will sometimes last longer. Oddly, the iridized black will start to look like the BE irid just before it burns off, very metallic silver and gold.

A question I've been asked several times recently - what happens to BE irid coatings at raking temperature? I've never tried it, and I can't recall ever seeing raked irid so I told them I didn't think it would survive. Is this a correct guess?

Brock
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Postby Brock » Wed Jun 25, 2003 1:30 am

A question I've been asked several times recently - what happens to BE irid coatings at raking temperature? I've never tried it, and I can't recall ever seeing raked irid so I told them I didn't think it would survive. Is this a correct guess?

It survives, I've combed it. Brock
My memory is so good, I can't remember the last time I forgot something . . .

tom suter
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Ird glass

Postby tom suter » Wed Jun 25, 2003 1:41 am

Spectrum reg ird stained glass can be used for draping & slumping. You have to stay under 1200 or metal coating will burn off it will also have cracks in the metal coating as it is forming over the mold. It will still look ok but not be as nice as when you started with it. Fused ird glass will not burn off at fusing temp, it was design for that thats the big difference one was made for fusing the other not. Tom

David Williams

Postby David Williams » Wed Jun 25, 2003 12:18 pm

Bob wrote:Hi Kitty,

I don't really know much about iridized glass other than that I have seen mottled or patchy coatings on glasses that were not made for fusing. I may be totalled incorrecty on the health hazard issue, and would really welcome comments from anybody that has real knowledge about irid coatings. Until then I would play it safe. I'm not only paranoid, I'm also conservative.

Cheers,


Spectrum irrid is mother of pearl luster or tera-isopropyltitanate, or what people also call titanium fume. There are other variations on the titanium/alcohol theme. There is another main one you can get which name escapes me. No it presents no health hazard in the kiln that I'm aware of, at least firing coated glass. Spraying it yourself is another story. Though it will usually burn out, you can fire it metal down against the shelf and keep it.

Bob

Jo Holt
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Postby Jo Holt » Wed Jun 25, 2003 7:46 pm

Bob wrote:Hi Kitty,

I don't really know much about iridized glass other than that I have seen mottled or patchy coatings on glasses that were not made for fusing. I may be totalled incorrecty on the health hazard issue, and would really welcome comments from anybody that has real knowledge about irid coatings. Until then I would play it safe. I'm not only paranoid, I'm also conservative.

Cheers,

Bob


I use irid baroque and was asked this question about safety. I didn't have any idea :shock:

So, I e-mailed Spectrum about their irid coating process and they said it was safe. Then I asked specifically about any change heating the coating in the kiln might make and they again said not to worry - that the coating was metals sprayed with an alcohol base; anything that could burn off has done so before the consumer gets the glass.

I also asked why the irid "disappears" when taken to fusing temps and they said the metals absorb into the glass & lose color becoming clear to the eye but are still there.

Getting this response eased my mind.

Jo (should have paid more attention in science class :roll: )

Michael Stevens
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Re: Dichoric & iridized

Postby Michael Stevens » Fri Jan 03, 2020 8:20 pm

has anyone tried to spray their own tin chloride? I have no access to iridized glass, I think it would be cool to add it to some of my scraps and make iridized frit bslla

Brad Walker
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Re: Dichoric & iridized

Postby Brad Walker » Fri Jan 03, 2020 9:17 pm

Michael Stevens wrote:has anyone tried to spray their own tin chloride? I have no access to iridized glass, I think it would be cool to add it to some of my scraps and make iridized frit bslla


Yes, I've done this. It's fairly hazardous: https://beta-static.fishersci.com/conte ... 25578B.pdf

Used to have the instructions in my book, but took them out after the first printing.

Tom Fuhrman
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Re: Dichoric & iridized

Postby Tom Fuhrman » Fri Jan 03, 2020 11:01 pm

As a furnace worker I used to spray tin chloride quite often as many glassblowers have done. It requires you to create a chamber that is well ventilated/exhausted and if used properly and carefully is not that dangerous. Some people I know even used silver chloride and Fenton even used ferrous chloride and got a copper looking iridescence. Like many things in the glass business, it just requires you to learn of the problems that can arise and then take precautions to avoid those problems. I think the same is true of our diets as well.

Tom Fuhrman
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Re: Dichoric & iridized

Postby Tom Fuhrman » Fri Jan 03, 2020 11:14 pm

If you were familiar with the production of catspaw and the formulations of it, you would realize why it disappears when it is heated to fusing temps. It never ceases to amaze me the people that haven't taken the time to visit glass companies and get an education on how difficult it is to make and keep consistent the material that they rely on so heavily. after having been in many factories one gets a better understanding of how important the companies that produce their materials are and what they do to satisfy their requirements. Spectrum used a totally different production technique than others such as Bullseye, Kokomo, and Wissmach. I've had friends that have worked for many of these companies and you'd be surprised how hard they try to please their customers requirements.
When I had some of my other businesses, I traveled to the suppliers I had to see what I was relying on for my lively hood. Don't take for granted that the flow will just keep flowing.
I had mentioned my concerns on the suppliers in the fusing industry about 6-7 years ago and some of those concerns have come to fruition with the closing and near closing of many of the major suppliers to the industry.


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