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  #26  
Old 08-30-2017, 02:30 PM
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Pete VanderLaan Pete VanderLaan is offline
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An important and frequently overlooked aspect of long element life is isolating the elements from the glass which does vaporize measured in micrograms per hour,. That involves a complete seal at the top of the pot.
The acid in your fingers is more than an ample source of causing element failures. We've discussed this many times prior to your arrival.
We've also discussed the importance of avoiding arcing in an element which is minimized by the use of an SCR. That we've discussed many times as well. Guage matters too. So does the glass you melt given the temperatures you have to melt at. There are lots of nuances in this little game.
Play nice or I'll let Richard run the show for a week. He'll never invite you to the Stampede and the stampede is a big deal.
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Old 08-30-2017, 04:02 PM
Kenny Pieper Kenny Pieper is offline
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Quote:
Originally Posted by Mitcheal Veenstra View Post
well, we just bought our first round of C cullet that arrived this week. It'll probably last us a year and depending on what's going on then we'll decide.

I'm a lot less leary of mixing and melting our own glass now since the class at Corning. We'll work on the phosophate colors this winter and I'll try a few melts of clear to get a feel of what we can do with our wire melters to have options no matter which way things go.
Michael did you know that phosphate colors need to get hotter than melting clear? Its sometimes not easy to get them into solution. I would be leery doing them in a wire melter. You might need a very aggressive flux to lower the melting temp but then it will also be aggressive to your pots and melter
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Old 08-30-2017, 04:09 PM
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I think that the substitution of Strontium for any calcium makes a really huge difference. You are no longer creating aphetite crystals which are the big ugly buggers we're so used to. If Strontium goes in, and it's not that expensive, most problems disappear. In a wire melter, I have not tried it but at 2300F it was easy. It has a similar factor as calcium so it's not hard to insert it.
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Old 08-31-2017, 11:25 AM
Jordan Kube Jordan Kube is offline
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You make a good point, Dan, even though your delivery was a bit off. People should not expect to get Richard's longevity out of wire elements.

I've melted fluorine cullet in a wire meter before. I got about a month, maybe, out of each set. I could walk in everyday and get a different reading on my ammeter, always lower. Ed Skeels melted fluorine batches in a wire melter and got 2 weeks out of a set until he switched to gas. Moly elements are worse, you hardly get a day. I have some pretty cool pictures somewhere of a customer of Steve's who didn't heed the warning.
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Old 08-31-2017, 11:35 AM
Bob Meyer Bob Meyer is offline
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When discussing element life, it's important to mention details like how many hours rather than years you get if you're discussing longevity. Dan has a point - a guy that fires up only on occasion (many, many hundreds of hours?) can easily have years and years on his elements, but not necessarily have bragging rights as to superior methods.

Under constant use, though (i.e., at temp continuously), I can't say I've ever heard of anyone getting past a year or two - with anything over a year (i.e., 8,000+ hours) being a real accomplishment. But my sample size is fairly small - if someone can get a consistent 15-20,000 hours out of their wire elements, I'd genuinely like to know how they do it.
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  #31  
Old 08-31-2017, 10:20 PM
Dan Vanantwerp Dan Vanantwerp is offline
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I installed a digital chronometer from Auber on my Glass Hive furnace and got it out to 9999 on the readout. BUT...I turn it down to 1250 during the week. I'm using the same electronics on the current setup so we'll see how long they go.

My controller includes a phase angle SCR and the elements are 11 gauge. I'm cooking at 2180 so it never gets screaming hot.

That's too bad to hear about the fluorine glasses and elements. Really takes a bite out the economy of making your own color if you factor that into it.

When I visited Ed while he was in Napa he had a whole pot of opal white. I was using powder to give practically all my stuff a white undercoat at the time. The thought of just dipping a nice thick coat of white was pretty inspiring.

Terrible delivery on my part to Richard. I can't stand the way our politicians can't seem to just have a civil conversation and there I go flying off the handle. Feel like such a hypocrite and I truly apologize.
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  #32  
Old 09-01-2017, 07:45 AM
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Shielding your elements entirely in a wire melter using a sealed baffle at the pot lip would help in the short term for making fluorine glasses but that's just one part of the problem. Fluorine is totally indiscriminate in how it sees fireclays and silicates. It eats them all. My big fluorine melter in New Mexico looked like melting ice cream on the walls, crown, door, crucible, blah blah blah. When You gathered, you could get a real hit of fluorine that was like smelling slats. Nothing pleasant about it. Phosphate opals are actually far more beautiful but far harder to melt as Kenny points out. It's best done with Gas and a lot of excess horsepower. As to pots, you replace them constantly.

Your wire melters all have essentially the same issue. They're a lot like electric golf carts. Step on the pedal and you are now going at top speed and top speed isn't going to work. There's no overdrive. No free lunch or something like that.
Something Donald Carlson was doing which seemed to work quite well was having a port in the furnace into which he actually stuck a blower and literally blew the fumes out about once every few hours.
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  #33  
Old 09-01-2017, 09:39 AM
Dan Vanantwerp Dan Vanantwerp is offline
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Star bars vs. fluorine?

Well, might as well carry this discussion out to completion in terms of furnace types. Anyone try a Star Bar (SiC) furnace for making opal colors? They've got more horsepower but are they any more (or less) resistant to fluorine?

Mark Laukner made a video on a 170lb Starbar...he gave me an early copy. Such a gracious person. It involves a lot of castable...do not come to this as a first project
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  #34  
Old 09-01-2017, 10:50 AM
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Star bars are just as bad except that they also react with simple silicates as well, so, worse likely. You can't melt fluorines in electric furnaces, not without dire and immediate consequences.
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  #35  
Old 09-01-2017, 12:54 PM
Dan Vanantwerp Dan Vanantwerp is offline
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OK...for theoretical interest. Has anyone ever struck up a TIG or MIG torch/gun without the gas turned on? Immediate and pretty nasty popping due to oxidation of the hot metal be it steel or tungsten. However, turn on the gas and you're good to go. So, if you evacuated the oxygen from the element chamber on a furnace what would happen? Don't think this is undoable...argon has killed weldors working in submarines and other sealed volumes because it fills the entire vessel or at least enough to leave little or no air to breath. It is heavier than air.

https://vacaero.com/information-reso...be-lethal.html

Hot air rises, but I'm not sure what hot argon does...

If you take Pete and Richards' suggestion of sealing the crucible chamber from the elements AND enclosing the entire lower structure in a gas proof chamber (maybe a nice, relatively thick stainless drum) could you stabilize a non-oxidizing environment around the elements. Would fluorine still attack elements in the absence of oxygen? Could a steady flow of argon be used to force out the lighter fluorine gas and keep the elements safe?
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  #36  
Old 09-01-2017, 01:27 PM
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Most electric heating elements rely on oxygen for their resistance to attack and aging. A1 elements form an aluminum oxide layer. You need oxygen for that. Moly elements need to be derated in a neutral atmosphere. Give this one a rest.
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Old 09-01-2017, 01:37 PM
Dan Vanantwerp Dan Vanantwerp is offline
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Inert gas, electric furnace (IGEF, patent pend.): RIP
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  #38  
Old 09-01-2017, 02:09 PM
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I'm pretty sure that altering the furnace chamber with various gases is common in industry. I seem to recall numerous references in the Kanthal literature on MoSi2 (in particular) and SiC that refer to various operating environments, and the corresponding performance specs.

Perhaps not necessarily desirable, or cost-effective at a studio scale, but apparently it's being done nonetheless.
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  #39  
Old 09-01-2017, 02:21 PM
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melting fluorines under any circumstances is a difficult proposition. Fluorine comes in a variety of monovalence forms by its nature. All release fluorine gas in varying degrees and fluorine is carcinogenic and sits atop the EPA list of bad things to breathe. So, you don't just have the furnace deterioration to consider, you have your own health as well. I really rarely melt them anymore but when I do, the building is turning over vast air changes. The Santa Fe Studio changed the air in the room once every 20 seconds. For fluorine, that's a good number.

This is a windmill best not tilted at. Either build a small gas melter so it's manageable or do it outside. Don't think electric.
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  #40  
Old 09-01-2017, 02:34 PM
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Snorting HF isn't fun.

I try not to think about all the stuff I've ingested up to this point.

Lemme tell'ya a story about this time the exhaust fan in the irridizing chamber was installed backwards,... blah, blah blah...
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Old 09-01-2017, 02:43 PM
Dan Vanantwerp Dan Vanantwerp is offline
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Has Dave Bross made fluorine opals in his glory setup?
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Old 09-01-2017, 02:43 PM
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Quote:
Originally Posted by Rick Kellner View Post
I'm pretty sure that altering the furnace chamber with various gases is common in industry. I seem to recall numerous references in the Kanthal literature on MoSi2 (in particular) and SiC that refer to various operating environments, and the corresponding performance specs.

Perhaps not necessarily desirable, or cost-effective at a studio scale, but apparently it's being done nonetheless.
That's what I'm referencing, Rick.
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Old 09-01-2017, 05:08 PM
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Quote:
Originally Posted by Dan Vanantwerp View Post
Has Dave Bross made fluorine opals in his glory setup?
*******
Don't go looking for exceptions to some well established circumstances Dan. If you don't have the tools, or the ventilation, you really shouldn't play.
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  #44  
Old 09-01-2017, 05:42 PM
Dan Vanantwerp Dan Vanantwerp is offline
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Quote:
Originally Posted by Pete VanderLaan View Post
*******
Don't go looking for exceptions to some well established circumstances Dan. If you don't have the tools, or the ventilation, you really shouldn't play.
Fair enough, Pete. Thanks for the warning.
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Old 09-01-2017, 07:06 PM
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Quote:
Originally Posted by Jordan Kube View Post
Most electric heating elements rely on oxygen for their resistance to attack and aging. A1 elements form an aluminum oxide layer. You need oxygen for that. Moly elements need to be derated in a neutral atmosphere. Give this one a rest.
The oxide layer forms in the elements fairly quickly I wonder if they were first oxidized if they could then hold up in a oxygen free environment. Innovation never rests. It relies on doing the things that can't currently be done.
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  #46  
Old 09-01-2017, 07:36 PM
Dan Vanantwerp Dan Vanantwerp is offline
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We need a glass "Mythbusters". I can just see those guys setting up a small prototype. I would use a vaping cigarette device in a chamber easily evacuated of all oxygen and see if it lasts longer than one exposed to air.

I'm kidding...but it would be fun
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Old 09-01-2017, 09:58 PM
Jordan Kube Jordan Kube is offline
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Innovation never rests. It relies on doing the things that can't currently be done.
Agreed. I'll leave this one for someone else to try.
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Old 09-01-2017, 10:04 PM
Dave Bross Dave Bross is offline
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No fluorines for me. Too much trouble and danger so I spent a good bit of time and effort finding what works with phosphates. I think the etched window glass in one of the West Virginia outfits from many fluorine melts was the final hint. The fluorines also shape shift on expansion and softening temps pretty quickly if they're sitting around hot. An example would be the (now historical) Spectrum opaque cullets. You could pick them up off a hot plate no problem but if you melted them in a pot the compatibility went way off.

If you want the info on how phosphates work best there's a thread on that in antiques and classics. Don't go with the first info you find there, read to the end. You could probably remove some of the things in my final recipe there, like the borax and nitrate. Be sure you get below the suggested amount of calcium and above the suggested amount of zinc. Use strontium for the modifer to replace the calcium. Anything else that would work, like barium, is toxic and has other problems.

I usually melted the phosphates in a wire melter and they went down nicely at lower temps. They work in the glory pots too.
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Old 09-01-2017, 10:51 PM
Dan Vanantwerp Dan Vanantwerp is offline
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Thanks Dave. This is an excellent footnote/preface to the thread you mentioned. Phosphates it is when I go that direction.
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Old 09-02-2017, 12:27 AM
George Vidas George Vidas is offline
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Kanthal actually does just as well in a neutral argon atmosphere as it does in oxidizing dry air. Presumably the oxide layer forms and doesn't dissipate.

http://www.hi-tempproducts.com/pdf/t...i-handbook.pdf

pp 11. "Table 3. Maximum Permissible element Temperatures in various Atmospheres."


Which brings us back to this question, from Dan V: "Would fluorine still attack elements in the absence of oxygen?"

If not, as cool as an argon flush is, you may as well just use air.

I wonder: could the efficacy of sealing the elements away from the glass with a gasket could be improved with slight positive pressure? I'm imagining harnessing the stack effect. A few small inlet holes at the bottom of the element chamber and a small vent hole at the top of the glass chamber. Maybe line that vent hole up with an exhaust snorkel.
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