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  #51  
Old 05-31-2021, 06:21 PM
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Originally Posted by Kenny Pieper View Post
Will,
I think that gold leaf will certainly work but is very expensive for the weight. Most people that I know making gold colors buy 24KY casting grains. Any jewelry supply store will have it.
Thanks - I hadn't thought about that - casting grains sound a lot easier to handle and a lot cheaper than gold leaf and buying them from a reputable jewellery supply store sounds a good way to get them (it's something I'd only want to buy from someone I trust).
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  #52  
Old 05-31-2021, 06:58 PM
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I buy fine gold shot 24 or grain, sold by the penny weight) 16 dw) from rio grande when I need gold. Quite honest and reliable. Leaf, or gold chloride is really pricey.

The process described in the Thuringen recipe book has been my beacon for how to make it over the last few decades. I have 3000 grams of the sands here available so I won't make more anytime soon although the 24 ct gold is here in the shop/.
Mary Beth is the only demand I have for ruby glass.
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  #53  
Old 06-01-2021, 11:21 AM
Josh Bernbaum Josh Bernbaum is online now
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Rio Grande is where I bought 5 or 6 grams of the casting grain 24K a couple years ago too. It dissolved fairly quickly in the aqua regia. I think I mixed 5g gold into 500g of sand which I've since used up. But Dudley G. gave me a few lbs. of some sands he made decades ago for which he dissolved part of an old gold coin, and when I get over my fear of lead (or when nobody else is around here, whichever comes first) I'll try it out. I think I love all the gold colors.
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  #54  
Old 06-01-2021, 12:35 PM
Larry Cazes Larry Cazes is offline
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Quote:
Originally Posted by Will Robertson View Post
Thanks - I hadn't thought about that - casting grains sound a lot easier to handle and a lot cheaper than gold leaf and buying them from a reputable jewellery supply store sounds a good way to get them (it's something I'd only want to buy from someone I trust).
I use a fair amount of 23k and 24k for fuming borosilicate. My go to for almost 10 years are local Pawn shops. Most have certified bars at spot.
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Old 06-01-2021, 01:47 PM
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Originally Posted by Josh Bernbaum View Post
Rio Grande is where I bought 5 or 6 grams of the casting grain 24K a couple years ago too. It dissolved fairly quickly in the aqua regia. I think I mixed 5g gold into 500g of sand which I've since used up. But Dudley G. gave me a few lbs. of some sands he made decades ago for which he dissolved part of an old gold coin, and when I get over my fear of lead (or when nobody else is around here, whichever comes first) I'll try it out. I think I love all the gold colors.
I understand your fear of lead. There are test strips available in the US designed to detect lead at concentrations down to 0.005 mg/L which is the CDC's maximum recommended lead level in drinking water.

I think it would be possible to have a small air pump (under 10 USD on eBay) draw some of your stack emissions through a bottle of distilled water or distilled water with a little dilute acid then measure the lead concentration in the water to get a measure of how much lead is being released in your stack emissions.

I read a lot about the Bullseye situation - their regulatory disclosures provided me with enormously valuable information on glass making. Their emissions control equipment sounded extremely expensive but I think emissions control on a much smaller scale might be vastly more affordable.

This gives an idea of the price of welding fume extractors available in the US:

https://www.ebay.com/sch/i.html?&_nk...fume+extractor

It might also be an idea to try hiring a welding fume extractor for a few days or a few weeks from an equipment rental company - then you could try it out and see how you get on without the cost of buying one or having to change the filters, etc.

Regulators and professional welders trust these machines every day to safely handle highly toxic fumes.
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  #56  
Old 06-01-2021, 02:59 PM
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Maybe one of those welding fume extractors could be modified, but I'm under the impression anyway that they wouldn't be up to the task of handling the several-hundred degree gasses coming out of my stack for the 4-6 hours of the melt cycle. It has to be close to the top of the flue for proper capturing. I feel good that my high-CFM ventilation system, which pulls from right above my stack and right above the door of my color furnace, is doing what it's supposed to do in removing the bad offenders. But it's the question of 'well what happens after it exits my shop' that still has me concerned. And I don't even have any pre-schools and residential areas right near my shop which sounds like was a big part of the issue in Portland years back. The Torit/baghouse filtration units look like the best solution but expensive as hell. Perhaps a custom smaller-scale one could be designed for a more accessible price, I don't know yet.
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  #57  
Old 06-01-2021, 03:11 PM
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Originally Posted by Larry Cazes View Post
I use a fair amount of 23k and 24k for fuming borosilicate. My go to for almost 10 years are local Pawn shops. Most have certified bars at spot.
I didn't know that!

How do you fume borosilicate? I've heard a bit about it but I know very little about it in practice. I'm planning to try to get Sn and Cu into a thin layer on the surface of glass from gaseous or liquid phase but in a furnace over a period of many 10s of minutes rather than from a flame. Your technique sounds very interesting.
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Old 06-01-2021, 06:37 PM
Larry Cazes Larry Cazes is offline
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I didn't know that!

How do you fume borosilicate? I've heard a bit about it but I know very little about it in practice. I'm planning to try to get Sn and Cu into a thin layer on the surface of glass from gaseous or liquid phase but in a furnace over a period of many 10s of minutes rather than from a flame. Your technique sounds very interesting.
Its deceptively simple. I pick up a very small amount of metal on a clear rod and introduce it into the torch flame very close to the candle ends. You will see the color of the torch flame change once the metal is vaporized and it starts to travel up the flame. Lastly I put whatever glass I want to fume on into the flame 6-8 inches away from the torch face and "paint" with the vaporized metal. There are lots of pictures on my accounts at facebook and instagram or at larrycazes.com
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  #59  
Old 06-01-2021, 06:58 PM
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Originally Posted by Larry Cazes View Post
Its deceptively simple. I pick up a very small amount of metal on a clear rod and introduce it into the torch flame very close to the candle ends. You will see the color of the torch flame change once the metal is vaporized and it starts to travel up the flame. Lastly I put whatever glass I want to fume on into the flame 6-8 inches away from the torch face and "paint" with the vaporized metal. There are lots of pictures on my accounts at facebook and instagram or at larrycazes.com
Thank you very much. Just sent you a friend request on Facebook.

Your work is phenomenally beautiful!

I didn't realize that this was possible using a metal - I'd only planned to try it using metal halides (silver chloride and copper chloride).

I don't have an oxygen supply so the flame temperatures that I can get are very limited (given the medical oxygen shortage in India I reckon it's not ethical for me to try and get an oxygen concentrator until the COVID-19 situation is under control).
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  #60  
Old 06-03-2021, 05:06 AM
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Maybe one of those welding fume extractors could be modified, but I'm under the impression anyway that they wouldn't be up to the task of handling the several-hundred degree gasses coming out of my stack for the 4-6 hours of the melt cycle.
Yup - there's absolutely no way that they could handle the very high temperature of exhaust gasses directly from our furnaces - the gasses would have to be put through a heat exchanger first to cool them.

Usually a heat exchanger transfers heat from outgoing combustion gasses to incoming combustion air to improve the efficiency of a furnace - after that the gasses should be cool enough to go into a simpler heat exchanger - just a long run of metal piping with small fans blowing air over it - to cool the gasses to the point that they can be put through a commercial welding fume extractor or filter system.

Commercial welding fume extractor manufacturers should be happy to disclose the maximum temperature that their units can handle.

Cooling the gasses before filtration also has the advantage that it will condense out transition metals from vapour phase to colloidal phase - making them much easier for the electrostatic precipitator and filters in a welding fume extractor to remove. It'll also greatly reduce the volume of gasses to be handled.

Another approach I'm looking at is to keep a lid on crucibles whenever I'm not removing glass and to use two crucibles one inside the other with the outer crucible kept at slight negative pressure and gasses removed from it put through a scrubber before monitoring and release - my hope is that keeping gasses escaping from crucibles separate from combustion gasses would greatly reduce the amount of gasses that need to be treated.

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It has to be close to the top of the flue for proper capturing. I feel good that my high-CFM ventilation system, which pulls from right above my stack and right above the door of my color furnace, is doing what it's supposed to do in removing the bad offenders. But it's the question of 'well what happens after it exits my shop' that still has me concerned. And I don't even have any pre-schools and residential areas right near my shop which sounds like was a big part of the issue in Portland years back. The Torit/baghouse filtration units look like the best solution but expensive as hell. Perhaps a custom smaller-scale one could be designed for a more accessible price, I don't know yet.
One of the companies in Oregon that got into trouble (I won't name them - we all know who it was) were emitting 3.5 tons of particulate matter per year from their stack resulting in arsenic levels in the surrounding air 149 times benchmark levels and cadmium levels between 59 and 200 times benchmark levels. The owners claimed that - while they could afford a second home - they could not afford to take measures to control these emissions. (Source: DEQ figures and other sources published in Portland Mercury.)

Benchmark air lead levels have been reduced to about a 10th of what they were back in the days when lead in petrol caused extensive lead pollution. There seems to be evidence that constant exposure to the high levels of lead in city air from vehicle exhausts did harm children.

None of us would ever contemplate causing emissions on anything like the scale that occurred in Oregon and most of us have never used arsenic or have eliminated arsenic from our recipes many years ago.

Thankfully, while lead is toxic it is significantly less toxic than arsenic.

On the scale that folk on this forum are working at, the cost of emissions control would be perhaps a thousandth of what it cost for the worst arsenic emitter in Portland glass-making in 2016.

I think for many of us, the cost of custom-designed emissions control isn't necessary and adaptations to our existing furnaces followed by one of the standard commercial units designed and regulated for use by the welding industry should be fine.

An extra layer of protection for your children would be testing your urine for lead and maybe other transition metals regularly - if lead or other transition metals escaped the safety measures they should show up in your urine - though transition metal levels in urine can also be affected by transition metals from sea food, etc.
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  #61  
Old 06-03-2021, 08:22 AM
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Gaffer simply ran an air conditioner right in front of the Torit filter to cool it. Otherwise, it melted.

The fumes and exhaust from a welding filter are simply not comparable to those on a furnace. The out gas , while far more intense in the melting stages continues as long as the glass is in the furnace. Lead emission in micrograms increases as the temperature of the furnace goes up, all well documented by Durk Valkema years ago.
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  #62  
Old 06-03-2021, 08:52 AM
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Eeeek! I'd want to cool the the exhaust gasses to within specifications before letting them anywhere near the filtration unit - gasses which are too hot would risk deforming the filter matrix and rendering the whole system ineffective.







I'm confident that through careful refractory and extraction design I can get good containment using standard equipment and techniques from the welding and chemical industries without any expensive special equipment.
****
Well, these were big kids. I'm glad you are confidant.
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  #63  
Old 06-03-2021, 10:56 AM
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well, these were big kids after all. I'm glad you are confidant.
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  #64  
Old 06-04-2021, 09:49 AM
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well, these were big kids after all. I'm glad you are confidant.
I've got an enormous amount to learn and an enormous amount of work to do before I can get to the point of testing whether or not my ideas work though...

With every step in glass making and refractory engineering there's 1 way to get it right and about 5 ways to get it wrong - I've usually blundered into all 5... 🙈
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Old 06-04-2021, 12:39 PM
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there's a lot more than five.

The differences in using a welders filter on a small amount of material is simply not in the same game as using a standard baghouse with McDonald Torit filters. I suspect that welders filters are not designed for continues use and furnace melts continue to give off vapor as long as they are hot. They just give off less as they are run more coolly.

I stopped making color rods about 20 years ago. I knew the business could be successful but I could easily see my parking lot filled with White Chevy Malibus with government plates. Once you start to bump up against STEL limits, the rules really change.

Arsenic is still in heavy use or there would not be Lead arsenate color rods also known as Enamel Whites available from Gaffer , Reichenbach and Kugler. Why the EU picked on Murano, I don't know. I strongly suspect that the same effect can be achieved with Antimony but it's just as toxic. I recall when John was buying the stuff by the container load for $2.30 per kilo. We had to deal with Noah Technologies nearer to $40.00.
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Old 06-04-2021, 03:40 PM
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Actually Noah is around $12lb, but they have a one thousand dollar minimum to place an order now
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Old 06-04-2021, 03:52 PM
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I was thinking in Kg's with small quantities. John's access was devastating.

Container's full.
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Old 06-05-2021, 12:09 PM
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Red face Refractory Materials

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documented by Durk Valkema years ago.
Thanks - I didn't know about him - been doing some reading on him...

What temperature do my refractory materials have to withstand for zinc barium silicate and borosilicate glasses? I'm using alumina crucibles and for the next furnace I'm planning an inner refractory rated to 1380 C / 2516 F and an outer refractory rated to 1310 C / 2516 F - will that be enough?

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I was thinking in Kg's with small quantities. John's access was devastating.

Container's full.
What on earth does someone do with containerfulls of arsenic?

Am I right in thinking that arsenic is only necessary for producing opaque glasses?

>Antimony

It's not helpful that the data sheets give LD50 but often no indication of the extent to which these metals bioaccumulate over time or their long-term toxicity. Folk still drink from pewter (510% antimony) - I admit that I wouldn't want to drink from it regularly...

Apparently a lot of our present-day knowledge of the human toxicity of selenium comes from an incident when a company making health food supplements containing selenium ballerkesd up and accidentally added far too much resulting in a few hospital admissions 🙈
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Old 06-05-2021, 01:19 PM
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At six percent arsenic in enamel glasses, it adds up rather quickly. Enamel whites are probably the most popular color base sold by rod makers.

If you want to think about the amount of glass made in studios alone these days, when Seattle Batch was mixing Gaffer's clear, the royalty he was to pay was a half cent per lb on batch sold. Gaffer cut him off when he was in arrears $35K. Do the math.

Both Arsenic and Antimony flip valences on the outer ring at differing temperatures but make both very useful in squeezing glass melts. Arsenic is not used so much now since it was more useful in lead based glass

Antimony is a principal ingredient in White metal a low temp casting material. both are in common use in the far east. Go to Monterrey Mexico and you'll find a very slick lead glass factory. The lead bi-silicate used here now comes up from there. Hammond only sells lead now out of Shanghai and used to make the mono-silicates in Indiana. When Fenton had its auction last year, one of the items was a barrel of antimony amulets as it said. I never figured out why they had that. While the EU may have banned cadmium, you can still buy the sulfide in the US for about $22 dollars a pound. Selenium is more expensive since China consumes lots of it in Steel manufacturing. So far it appears that the supply of such things is not affecting the German rod people at all. Access to crucibles is another matter.
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Old 06-05-2021, 03:22 PM
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At six percent arsenic in enamel glasses, it adds up rather quickly. Enamel whites are probably the most popular color base sold by rod makers.
That's good - one thing that fascinates me about glass is that it provides a clear medium in which colour and refractive index can exist independent of surface. Because opaque glasses bind colour to surface I tend to lose interest in them so happy to live without arsenic.

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If you want to think about the amount of glass made in studios alone these days, when Seattle Batch was mixing Gaffer's clear, the royalty he was to pay was a half cent per lb on batch sold. Gaffer cut him off when he was in arrears $35K. Do the math.
Was that where the container load of arsenic went? Glad I don't live downwind of that smokestack...

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Both Arsenic and Antimony flip valences on the outer ring at differing temperatures but make both very useful in squeezing glass melts. Arsenic is not used so much now since it was more useful in lead based glass
Could you explain more about that please? I'd heard a bit about that but not fully understood it - because arsenic and antimony flip valence state with temperature they can change from oxidising agents to reducing agents as the temperature of a batch changes? I can see why that might be extremely useful in some glasses where you want one oxidation state to get a metal to dissolve then a different oxidation state to give the required colour - reckon that it would be a big help to understand it better when interpreting old recipes.

What does "squeezing" a melt mean?

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While the EU may have banned cadmium, you can still buy the sulfide in the US for about $22 dollars a pound.
I'd noticed that...

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Originally Posted by Pete VanderLaan View Post
So far it appears that the supply of such things is not affecting the German rod people at all. Access to crucibles is another matter.
I remember William Gillinder discussing that... Do you use giant versions of the little alumina crucibles that I use? I just chose alumina for the crucible material because it seemed like the best thing I could find - vague plan is to get as far as I can with alumina then change to much more expensive silicon carbide (carborundum) crucibles if the alumina ones start breaking or dissolving...
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Old 06-05-2021, 04:54 PM
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Do get back to me about using Silicon Carbide. Your slip is showing.

I'd suggest you refer to the archives, Glassnotes, Volf, Morey, Weyl, Hodkin and Cousen and others.

Gaffer didn't have emissions. They used full filters and baghouses. John was a very conscientious guy. I feel fortunate to know him.

I'm not an endless well of knowledge surrounding basics and I somewhat expect people to do a bit of their homework eventually. Currently my patience account feels overdrawn. Just use the archives. They're very good. Melt a few thousand pounds of colored glass.
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Old 06-06-2021, 12:13 PM
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Do get back to me about using Silicon Carbide. Your slip is showing.
Sorry - you commented in 2017 "Silicon carbide is highly reactive with glass. Just sayin'" - so I can use SiC as a microwave susceptor in furnaces but definitely not on anything that comes into contact with glass...

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I'd suggest you refer to the archives, Glassnotes, Volf, Morey, Weyl, Hodkin and Cousen and others.
Who are Morey, Hodkin and Cousen?

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Gaffer didn't have emissions. They used full filters and baghouses. John was a very conscientious guy. I feel fortunate to know him.
Thank you very much. Is John both John Croucher and John Leggott?

For other people reading this here's a link to Gaffer's Environmental & Sustainable Development page - they seem to have been 10 years ahead of their time in installing filters and reducing emissions to less than 1/10th of allowable limits http://www.gafferglass.com/informati...e-development/

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I'm not an endless well of knowledge surrounding basics and I somewhat expect people to do a bit of their homework eventually. Currently my patience account feels overdrawn. Just use the archives. They're very good. Melt a few thousand pounds of colored glass.
Regarding arsenic opaque glasses - which I don't have any interest in - haven't they been overtaken by your work with Mark Peiser on the Marko Blanco titanium opaques which are superior from both an artistic and a toxicological perspective?

My patience account ends up overdrawn at times as well - I co-founded the reference dictionary of Scottish Gaelic www.faclair.com - over the last 10 years it's been an enormous amount of work and we receive no funding so it's an substantial drain on time and resources - it's used extensively by government, universities, schools and broadcasters and changed the face of Gaelic learning and teaching.

You've pioneered glass making not only for your generation but also for the next generation and I can definitely understand you feeling badly overdrawn at times.
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Old 06-06-2021, 01:01 PM
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When Nick Labino was still alive, he would pretty much ignore you unless he thought you had really done your homework. If he thought that, he would talk about stuff. My impression here is that you need to do just that.

John Croucher is the individual behind the chemistry at Gaffer. Leggot learned the material over the years but in a rote sort of way. He was the businessman. Torit filtration was established long before Gaffer. Federal and State ignorance viewed this community as too small to consider until the lichen samples in Portland set off the alarm. Bullseye knew the toxicity levels, they simply didn't think they'd stick around. Uroboros was contaminating the neighborhood with Fluorine and did not have the capital to install baghouses. Bullseye claiming ignorance is not supportable.

Simply put, you need to read some basic texts on what glass is. Properties of Glass ( Morey) is a cornerstone text. textbook of glass technology ( Hodkin and Cousen) Charles Bray has some fairly superficial stuff. Vargin on enamels, Abe Books can be a good source.

Silicon carbide at perhaps 25 grams in 20 lbs added would indeed be a reducing agent for a short term. A crucible made from it will make a foaming cleanser before it vanishes entirely, perhaps a full day.

You are making crushed cullet melts of 65 grams. Very hard to learn from that. I submit the differences in the two areas have very little in common. Going to school would be a best bet. Univ of Missouri and Penn State both have very good Ceramic Engineering programs and Alfred University in New York is wonderful. All offer full degrees .
We pursued the phosphate opaque with the class I gave in 2013 and had mixed results. Mark kept after it on his own with me doing all the expansion measuring. Eventually he (after 200 melts) had a white that was indeed denser than the arsenate but it has issues. It can't be rolled in rods and has to be cast, a problem. It has had rather limited success catching on and I strongly suspect the Italians of continuing to make the arsenate when no one's looking. Bullseye melts it for him. Olympic sells it. On the rare occasions I want the white, I make an arsenate. I prefer to buy it from East Bay.

While I had hoped that the bulk of studios would want to pursue their own materials, I'm clearly wrong about that. Answering targeted questions such as yours really require that you have already immersed yourself in the basic stew that is made doing melts daily and using them to make things. You need the stew. Trying to dissolve gold without acids, making ruby without lead, melting in exotic pots, never using lead are all ways of avoiding the stew calling you. There are a million things to do wrong that have yet to get covered here. While I am receptive to some very basic sustained questioning, I'm not inexhaustible. What I fear seeing is incorrect information.
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Old 06-06-2021, 05:18 PM
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Alumina crucibles will not hold up to borosilicate glasses in the long term at elevated melting temperatures. If you want to melt boro from scratch at 28-3000 degrees F you will need to use AZS. Above the glass line you will want a 32-3400 degree F refractory. If you're serious about this I suggest you do a heat flow calculation for your refractory profile. Thinkhwi.com has a good one. Even if the products aren't available where you are there are a lot of similarities between compositions and conductivity between manufacturers and you can substitute in a similar HWI product to get a good ball park estimate.
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Old 06-06-2021, 06:14 PM
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Quote:
Originally Posted by Jordan Kube View Post
Alumina crucibles will not hold up to borosilicate glasses in the long term at elevated melting temperatures. If you want to melt boro from scratch at 28-3000 degrees F you will need to use AZS. Above the glass line you will want a 32-3400 degree F refractory.
Thank you very much! It looks like that's the way to go - move to higher zirconia content (and higher price) AZS crucibles as ability to withstand higher temperatures is required.

I'll start off with alumina while I'm trying out new things - probably wrecking a lot of crucibles along the way - then once I've got things perfected move over to AZS crucibles. (I suspect that initially errors and redesigns on my part will be the main limiting factor for crucible life then later on the corrosiveness of the glass and the effects of the high temperature for boro.)

Quote:
Originally Posted by Jordan Kube View Post
If you're serious about this I suggest you do a heat flow calculation for your refractory profile. Thinkhwi.com has a good one. Even if the products aren't available where you are there are a lot of similarities between compositions and conductivity between manufacturers and you can substitute in a similar HWI product to get a good ball park estimate.
Thank you very much for mentioning thinkhwi.com - it's great to see a refractory manufacturer with experience supplying the glass industry - most refractory manufacturers over here have never supplied a glass-maker and so have no idea of the temperatures involved and no products which can withstand these temperatures. thinkhwi.com has been great to learn from a supplier that does have experience supplying glass making

I wasn't able to create a logon to the thinkhwi.com site to get to the heat flow calculator - I don't think it likes European addresses and threw error messages - I'll try again tomorrow. Would be good to have something better than my present rough calculations based on crude steady-state approximations. I was able to get my paws on a PDF of the 2005 Harbison-Walker Handbook of Refractory Practice though which looks like a very useful book - I've been trying to find a good book on refractory engineering for a few years but not been able to find one. The Applications section at the end doesn't give an example of a glass furnace but a lot of the information in the document seems very relevant to what we're doing.

Josh mentioned the temperatures that his furnaces run at and I realized that the 1380 C / 2516 F fire bricks that I can get from a supplier here won't be good enough for the inner refractory so I'm searching for a supplier who can supply fire bricks with a higher temperature rating at the moment.
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