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  #26  
Old 02-15-2020, 08:31 AM
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My mistake. Itís a 200 lb crucible. One scoop then wait 1 1/2 hours


Shawn, what size is your crucible?
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  #27  
Old 02-15-2020, 09:30 AM
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Quote:
Originally Posted by Pringle Teetor View Post

has anyone seen seeds seeds this bad in bomma?
*****
Does the cullet have tiny seeds in it before you melt them?
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Old 02-18-2020, 08:28 AM
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Could loading too slow be a problem? I know the first cristalica I got was the bird turd shape not the patties. If I loaded too slow with the bird turd shape I got lots of small bubbles. If I loaded faster the hole in the shape gave larger bubbles deeper but these took the small bubbles with them when they came up and gave me great looking glass. With the patty shapes the glass had more small bubbles Just a thought.
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  #29  
Old 02-18-2020, 11:25 AM
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At this point, I would at least need a percentage analysis on the batch to hone in on the issue. If it's seed free AND David can torch out a cord, I turn right away to an alkaline flux and the inclination is lithium but I don't know that. Borax is another possible one but less likely to torch out. Lithium would make it a lot more expensive to make. Fluorine is yet another possible but also less likely. I have heard it's rather long working and that again supports Lithium.

It's also possible the batch is reacting with the furnace liner. We know nothing about the age of the equipment. In that capacity, I would not expect the cords to be torchable.
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  #30  
Old 02-18-2020, 12:08 PM
Shawn Everette Shawn Everette is offline
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I thought it was established earlier on in a different tread that it was a lithium based glass, sans borax. It was one of the selling points.
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  #31  
Old 02-18-2020, 02:07 PM
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I just don't recqll it but lithium is quite capable of causing cords all by itself. The fact that David could torch out a cord has a lithium presence to me. If you can find the source claiming the presence of lithium, I'd appreciate it.

Way back around 1975, Henry Summa and I made a lithium glass that was incredibly thermal shock resistant. You could just keep it out of the glory hole forever. Then, on the third day it was the most cordy glass I''ve ever seen. I'll never forget it.
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Old 02-18-2020, 03:03 PM
Shawn Everette Shawn Everette is offline
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http://talk.craftweb.com/showthread....ium#post143354

This might be it.
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  #33  
Old 02-18-2020, 05:31 PM
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When Nick Labino initially wrote the formula for SP, it was a good deal higher percentage than what was finally settled on. I recall it as SP92. The issue was the lithium content and it was dissolving the furnace so, Nick cut it back to where it is today for the SP87. There are other SP formulations but are not commonly in use but they do fit Kugler's opaques which were lower in expansion. Those Kuglers did not then, and do not now fit the standard issue of SP87. It was , I believe marketed as SP83.

Lithium is a profound flux. John Croucher identified, through Appen I recall that the expansion factor should in reality be 4.92, a big jump from the 2. whatever it had been at. Glassnotes IV did take note of that change in that edition at my urging .

Bottom line is that it's a two edged Sword. Since I have no idea which formulation Charlie was in search of at the time he decided to go to melt in the Czech Republic. it's a very tricky material to dance with. Also, it's really expensive. The last time I bought it, it was over $500.00 a fifty lb bag and it had gone up a good deal since then.

What I'm sifting through right now as to cords does sound like a lithium influence. It will eat a furnace alive if excessive. The stuff Eben refers to is not material that can be evaluated at this point.

In my mind, SP87 is the reliable material of choice.
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Old 02-28-2020, 10:03 AM
Shawn Everette Shawn Everette is offline
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Just found my SDS, lithium confirmed, less that 1%.
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