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  #26  
Old 07-21-2018, 03:56 PM
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Pete VanderLaan Pete VanderLaan is offline
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It seems to me that when you pick up too cold, you get microcracks in the rod pieces which show as bubbles later. That can occur as well when color is put into an already heated color box. It's also why making your own frit by quenching absolutely sucks. Just a million bubbles. Frit needs to be made in a crusher with serious cleaning after the crush. A good crusher is really pricey.
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  #27  
Old 07-22-2018, 12:26 PM
Rich Arentzen Rich Arentzen is offline
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Thanks.

We put 4" color bars in a cold pick up box. Heat up over 45 minutes or so to a temp that will slump the bars slightly by end of the day.

Some batches are acceptable some are not. We have been using Kugler mostly and the last few batches have been very difficult for us.

We have some Reichenbach now which is decent. The Reichenbach tends to strike more easily and is prone to small dense nuggets around 1/32 in diameter that can be seen after the fact as leaving a black dot effect in the lighting. The gaffer has a tendency to have many small pin holes in the surface.

We make up to 100 pieces of lighting components daily, mostly in white. The pieces often look great until we shine a light in them.

For efficiency, we have been clipping the color directly onto the end of the pipe. There is basically no time for overlays considering the tight margins.
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  #28  
Old 07-22-2018, 12:54 PM
Jordan Kube Jordan Kube is offline
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On a collar or right on the pipe?
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  #29  
Old 07-22-2018, 06:13 PM
Rich Arentzen Rich Arentzen is offline
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We switched from a collar to straight on the pipe with no worse results and quite a bit more straightforward in production. In fact, we no longer even blow a starter bubble into the color. That works great too. (similar bubble content)
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  #30  
Old 07-22-2018, 09:41 PM
Eben Horton Eben Horton is offline
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Heres a suggestion. Get an ultrasound machine and use it on your bars. Find the flaws and mark the bars with a sharpie marker and diamond saw the flaws out by avoiding where you marked the bar. Gaffer does this
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  #31  
Old 07-23-2018, 09:09 AM
Josh Bernbaum Josh Bernbaum is offline
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Quote:
Originally Posted by Rich Arentzen View Post
I can no longer take picking up bars of white littered with bubbles. Since we are surrounded by restaurants etc, I am also not too keen on melting white batch. I have been thinking of either finding a white cullet source or melting commercial frit in small batches. The Skutt kiln may be appropriate for that use. Anyone doing this? Any other ideas, including melting our own dense white in a very safe manner?
It seems to me Rich that your process of using color bars for making 100 pieces a day with the same color is highly unusual in the history of production-style blown glass. It's so much cheaper to mix and melt your own, and if you can get away with just a fluorine (as opposed to the lead arsenate enamels it sounds like the bars are), then safety-wise it's just the fluorine off-gassing. Ventilation moving air properly is important of course. I've found that leaving the gathering temp for that as low as possible (like in the 1800's, seriously) reduces volatilization and prolongs the amount of time it stays opaque. It's daunting and will be a learning curve, and you will need a dedicated gas furnace, but you're not in Portland Oregon so might as well take advantage of that fact while we still can. A fluorine batch will melt at low temps and quickly and doesn't need a day to fine out like some things. There's lots of help here to get you started with all of this too.
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  #32  
Old 07-23-2018, 09:27 AM
Rich Arentzen Rich Arentzen is offline
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Thanks Josh, Safe for workers and neighbors? I am happy to have someone come up and consult with us and really help make it happen in a predictable way. I could get Glasma to mix the white batch additive for us as well. Even though we melt batch, I am apprehensive of that next step, mostly due to safety concerns.
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  #33  
Old 07-23-2018, 10:04 AM
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It actually doesn't sound to me like a lead arsenate. It sounds to me like a fluorine opal with pinholes all through it. Those will never ultrasound out.

I agree with Josh that the efficiency of what you are doing is highly questionable. 100 pickups a day would be far more easily done in a pot, likely with a small venturi burner below the pot on the side. In melting fluorines, it takes me about three hours to go from adding the batch to having the stuff ready to use. It is never melted higher than 2200F at the very end and most of the melt occurs below 2100. Then it's plunged to 1900-1950 to work it. It is corrosive as can be.

I would not agree that "It's just fluorine offgassing" . It demands respect.
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  #34  
Old 07-23-2018, 11:15 AM
Josh Bernbaum Josh Bernbaum is offline
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I would not agree that "It's just fluorine offgassing" . It demands respect.
I've been curious about this for a while. It's fluorine gas that can mix with the moisture in the air to form HF, am I correct? That is of course concerning from the standpoint of "what are we breathing" near or in the neighborhood of one of these melts. I've seen a couple etched windows in other folks' shops before. I've also heard a story of someone who had a permanently hoarse voice after gathering these glasses for an extended period of time. I am still kind of surprised that fluorine isn't (yet) in the EU's crosshairs. I'm kind of a nervous type of guy, and actually put a piece of glass (not boro) right next to my gas furnace's flue vent where it exits out of my building and kept it there over the course of several melts. No etching whatsoever. I'm curious if there any other underreported/undocumented health issues from fluorine melts in the absence of other chemicals?
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  #35  
Old 07-23-2018, 11:31 AM
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When I met with the head of the Wash State OSHA back when I was running the tech section for GAS, he was very clear that Fluorine was a the top of their agencies cancer causing materials. I think in the last 18 months, federal OSHA has been effectively gutted at the EPA level to not push on that. Bullseye has the beginning of their 1.2 billion dollar class action suit starting in Oct.

Differing formulations yield differing results. I always had best control using cryolite. Sodium Silica Fluoride often smoked from the pot. Uroboros windows were totally etched and Eben Horton had that problem in his studio using a specific batch formulation.

What the gas needs is moisture to create a weak HF solution. Weak being enough to etch windows. It may be the case that putting the glass right at your flue is not moist given the heat.

I don't melt glasses like that casually. I haven't done any since the color class actually but I have not needed any in my work. I would melt them but with the vents on full. At the class, we did them outside if you recall. I would not be intimidated melting a 7 inch pot of the stuff particularly but I'd keep the temperature as low as I could get away with. If you recall, Durk Valkema did a most interesting study of microgram release per hour based on temperatures.

I have to come back to this again though. Actuarially, glassblowers are dying of tobacco and alcohol, not studio exposures. I'm at almost 50 years in. Alcohol will get me for sure.
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  #36  
Old 07-23-2018, 01:15 PM
Eben Horton Eben Horton is offline
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Quote:
Originally Posted by Josh Bernbaum View Post
I've been curious about this for a while. It's fluorine gas that can mix with the moisture in the air to form HF, am I correct? That is of course concerning from the standpoint of "what are we breathing" near or in the neighborhood of one of these melts. I've seen a couple etched windows in other folks' shops before. I've also heard a story of someone who had a permanently hoarse voice after gathering these glasses for an extended period of time. I am still kind of surprised that fluorine isn't (yet) in the EU's crosshairs. I'm kind of a nervous type of guy, and actually put a piece of glass (not boro) right next to my gas furnace's flue vent where it exits out of my building and kept it there over the course of several melts. No etching whatsoever. I'm curious if there any other underreported/undocumented health issues from fluorine melts in the absence of other chemicals?
Put the piece of glass in the coldest area of your shop and wait for condensation to work itís magic. Near the flu is as dry as it can be and wonít produce hydroflouric acid. Windows etch because one side is hot and the other side is cold in the winter.
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  #37  
Old 07-23-2018, 01:42 PM
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And if you do what Eben suggests and the glass etches, your exhaust system is a failure.
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  #38  
Old 07-23-2018, 03:28 PM
Rich Arentzen Rich Arentzen is offline
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So I agree it is inefficient, however, I'm not hearing anyone make a strong case for the melting of white being safe for the workers or the neighbors. Am I wrong about that?

Last edited by Rich Arentzen; 07-23-2018 at 03:37 PM.
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  #39  
Old 07-24-2018, 08:56 AM
Josh Bernbaum Josh Bernbaum is offline
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It seems difficult to find any studies that have been done to fully answer the question of exposure to fluorine gas coming off of glass melts. This might be a good topic for the Rakow library to help research.. Aside from the acute, deadly stuff dealing with direct exposure to HF, what little I could find online seemed to indicate respiratory/nasal irritation from limited exposure to fluorine gasses. It's most likely safer to be around than many other toxic things that go into some melts, but it obviously can't be healthy. Optimal ventilation will get it out of your building properly, but then there's the other question that many (besides maybe the DEQ in Portland, for better or worse) don't seem to consider much which is what happens to these compounds after you blow them out into mother nature (and neighborhoods). I'm reconsidering my suggestion given that unknown, and that it sounds like you have multiple employees and close neighbors. Would your customers be okay with a sandblasted surface on the lighting? Maybe that would hide some of what you're seeing. Just another thought.
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  #40  
Old 07-24-2018, 09:18 AM
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I just don't tend to see small pots of it as an issue- 21lbs or less. I think if exposure was an issue with neighbors, it could be melted around 4:00 AM. It's ready to go in three hours or less if you do it properly and the main gassing is gone. Turn it down to 1950F and work out the pot, assuming it's first gathers making the opal.

Wash State certainly thought Fluorine was a big deal. The seemed quite mollified if the ventilation was good. In the bullseye DEQ stuff, the big concern was with Arsenic and spread to Hexavalent Chromium and cadmium. The air sampling was really high. I don't really know what will happen with the class action suit since I was under the impression that actual harmful effects were at least hard to prove. Uroboros, which indeed had all the windows etched was never pursued by DEQ on that basis. Meeting the consent decree for baghouses and Torit filters was not economically feasible there, so they threw in the towel.
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  #41  
Old 07-25-2018, 09:13 AM
Dave Bross Dave Bross is offline
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Welcome to phosphates...the glass of the 1800s and the future.

Take the long view...you'll be screwed in the future if you're depending on highly toxic glass.

That would be physically or legally screwed.
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  #42  
Old 07-25-2018, 09:31 AM
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Phosphates occupy a tiny fraction of the market and require the uses of interesting modifiers to melt them without a great deal of trouble. I'm not at all sure that if Phosphorous became a serious player that it wouldn't get a great deal of scrutiny.

Currently the EU is even thinking about cobalt. If that's true, absolutely nothing should be thought of as safe.
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  #43  
Old 07-25-2018, 09:02 PM
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Quote:
Originally Posted by Pete VanderLaan View Post
Currently the EU is even thinking about cobalt. If that's true, absolutely nothing should be thought of as safe.
Speaking of cobalt. I wonder if it'll be "clean" cobalt.


https://www.bbc.com/news/business-44732847
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  #44  
Old 07-28-2018, 09:58 AM
Dave Bross Dave Bross is offline
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"Interesting modifiers" may be the way forward.

Strontium could take us very close to the desirable qualities of lead crystal with better coloring possibilities.

Less expensively too.
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  #45  
Old 07-28-2018, 12:20 PM
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depends on where you are. I once suggested it to Croucher and he said the nearest place using strontium was 10,000 miles way rendering it inaccessible and unaffordable. No matter how you add it up, phosphates are simply more difficult to melt than conventional glasses.
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  #46  
Old 08-03-2018, 08:08 AM
Eric Trulson Eric Trulson is offline
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The problem of safely dealing with small quantities of fluorine gases in a hot-shop suitable manner has been knocking around in my head for the past week or two and refuses to leave.

I found a great resource on the EPA website when I was looking into it more (a gov't document from the 70's on safe disposal & neutralization of certain compounds). The section on fluorine is from pages 25-30 within the document:

https://nepis.epa.gov/Exe/ZyPURL.cgi...y=91007R6C.txt

From what I read there, it sounds like passing the fluorine-rich furnace exhaust through a bed of charcoal would convert the available fluorine gas into carbon tetrafluoride, which is (apparently) inert and nontoxic.

Anybody with more chemistry chops than me know how you might test the results of a system like this? Specifically, how you could measure the exhaust gas coming out of the charcoal bed to find the fluorine levels in ppm and see if you'd successfully neutralized things or not. Is that a gas chromatography/mass spectrometer sort of problem, or are there cheaper sensors that might work that I don't know about?
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