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Brian Wong Shui 05-22-2017 11:02 AM

Casting Boro
Anyone know what it takes to melt boro glass for casting. 1700 lbs worth. CAn you even melt this stuff in a conventional moly furnace? Where would you get batch.

Crazy RFQ that came in.

Pete VanderLaan 05-22-2017 02:26 PM

Don't even think about it in your furnace. The crucible is not designed for Boro.There is enormous waste that has to be skimmed. Indeed a moly theoretically can do 2750F in terms of heat generated but your refractories will get even with you.

Boro cullet is being melted at 2380. For the most part it's very seedy stuff and not particularly fluid at 2380. It is melted.

I can refer you to the old boro formula for batch from 1915-1925 when it was being trademarked and patented.

It is also expensive as a cullet. There are lots of boro makers who would likely buy the cullet at well over a dollar a lb. Well over. That's where to make your money.

Brian Wong Shui 05-22-2017 02:36 PM

Pete, thanks for the facts to put beside the gut instinct to say no.

Eben Horton 05-22-2017 05:57 PM

Why boro ?

Brian Wong Shui 05-22-2017 09:21 PM

No idea. Material was listed on the RFQ for a project. Sometimes I don't want to ask too much. I think that they are trying to do something like....

on a much smaller scale.

charlie jenkins 05-23-2017 06:05 AM

Talk to this guy.

Oakland CA artist has (or had 12 years ago) a Boro casting furnace.
Really cool.

Pete VanderLaan 05-23-2017 08:55 AM

I never knew David to have boro casting. He certainly cast some beautiful stuff in soda Lime. I well remember utterly destroying a big marver with him one night at Pilchuck in the earlier days.

Greg Vriethoff 05-23-2017 04:31 PM

If you browse the images on his site some of the large sculptures, as well as table and counter tops, list "pyrex" as a material used.

That doesn't necessarily mean he has/had a furnace. Many look like they are cast from chunks rather than hot poured.

I'm still wagering you won't find a private studio with the infrastructure to melt boro from a raw batch formula. The bong suppliers are doing it with cullet.

Pete VanderLaan 05-23-2017 05:44 PM

I thought Brian meant to use a hot cast. Chunk de Verre is possible in a kiln like the ones in david's website but it would not be what I would call a clean casting, not by a long shot.

David Schimmel 05-24-2017 06:40 AM

Last time I talked to David....
...he was casting ophthalmic crown cullet, sometimes from Schott, and when Schott moved ophthalmic production to Germany, he sourced overstock ophthalmic crown from Mexico. This would have been at least 10 years ago, though.

Pete VanderLaan 05-24-2017 07:06 AM

SO, was that the BK7?

Sky Campbell 05-24-2017 10:44 AM

What's the problem? Gas furnace lots of heat the pot will hold up longer then you think as long as you keep it hot. Boro cullet can be had relatively inexpensive (a buck a pound or less for broken rod and tube)

"Infrastructure" doesn't that define glassmaking?

Pete VanderLaan 05-24-2017 11:31 AM

We don't recommend a 90% alumina pot for melting Boro. It would be far more appropriate to use AZS but the thermal shock issues are huge. I am constantly told that the scumming from the interaction between that glass and the pot is excessive. You can always tell a glassblower but you can't tell him much is the saying around here.

Steve Stadelman 05-24-2017 01:33 PM

25-26 years ago I did some large boro castings in the neighborhood of 150 pounds, chunk casting in a kiln. At 2350 it took hours just to level out in the mold and have most of the large bubbles come to the top. What a pain in the ass.

David Schimmel 05-25-2017 06:14 AM

Nope, David was casting S1, the most common ophthalmic glass - when people were making/wearing glass lenses (you'd be hard pressed to find any today, especially in this land of liability).

Pete VanderLaan 05-25-2017 07:53 AM

I certainly remember all of those pucks that were outside in the scrap.
I really miss my all glass lenses. If you spend any time around grinding equipment, you know why. I still have one pair with a polaroid prescription but they're pretty dated.

David Schimmel 05-26-2017 06:06 AM

Despite what your dispenser will tell you, glass lenses are still available in this country. Plastic lenses are not really "safer" than glass lenses, but they're a hell of a lot more profitable - eyecare "professional" my ass.

Pete VanderLaan 05-26-2017 07:17 AM

more like eyeware profiteer... I don't get my eyes "checked : anymore. I go to an ophthalmologist now and the difference is really remarkable. He also owns the processing portion. I get really much better glasses now than I ever did.

I think the thread has officially been hijacked at this point.

Eben Horton 05-26-2017 08:00 AM

I just had to get glasses for reading. It's an emotional thing as now I fully feel like an adult/grown up/over the hill.

Pete VanderLaan 05-26-2017 08:30 AM

Once you're over the hill, you pick up speed... really.
Once my eyes started to fail perceiving these 20mu bubbles in glue beds for the big optical work, I had to stop doing it. Bubbles really get bigger and flatter in glue beds when you squish them. What I would think was perfect looked awful the next morning. I also found I had a lot of trouble playing softball at night in leagues. Aging sucks actually.

Art Freas 05-26-2017 03:50 PM

A side note, you can get bifocal safety glasses really cheap at Lowes, lie 13 bucks cheap. No magnification for distance and then a section at 1.25 and up for near.

Eben Horton 05-26-2017 05:08 PM


Originally Posted by Art Freas (Post 135126)
A side note, you can get bifocal safety glasses really cheap at Lowes, lie 13 bucks cheap. No magnification for distance and then a section at 1.25 and up for near.

Good to know. Thanks !

Pete VanderLaan 05-26-2017 05:37 PM

And seeing a specialist can actually save your eyesight

Eben Horton 05-26-2017 05:50 PM


Originally Posted by Pete VanderLaan (Post 135128)
And seeing a specialist can actually save your eyesight

Yes. I went and saw an eye dr.

Pete VanderLaan 05-26-2017 06:45 PM

Good. There's a huge difference between an optometrist and an ophthalmologist.

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