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Old 11-16-2020, 06:57 PM
Ryan Turner Ryan Turner is online now
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Why are there so many soft glass COEs?

I've been working soft glass for a long time and just realized I can't actually answer this question. How did they come about? Is 90, 96, 104... just an accident of history, or is there some particular reason why these COEs are most suited to their common applications?
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Old 11-17-2020, 11:11 AM
Shawn Everette Shawn Everette is offline
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It's most likely a result of manufacturers creating a base glass for specific applications. 90 is a great fusing glass, but garbage to blow. 96, depending on source, can be a good for fusing or blowing, but rarely great for both. 104 was designed for lampworking when you still had to pump the bellows yourself. There are always exceptions, but that's probably it in a nutshell.
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Old 11-17-2020, 11:14 AM
Art Freas Art Freas is offline
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"90 is a great fusing glass, but garbage to blow" Very true, I took a rollup class and we used bullseye 90 for the rollups and then blew them out. You had to heat like you were going to spin it out and then work it quick like it was a goblet. At the time I was used to the short working time of the Sys 96 Studio nuggets so I was passable at it. The folks that were used to the longer Spectrum Premium 2.0 were not having fun at all.
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Old 11-17-2020, 02:23 PM
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Pete VanderLaan Pete VanderLaan is offline
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you should go look at a thread in Antiques and classics about the beginnings of the term COE which as I recall originated at CR LOO in the mid '70's. The thread was started by Lani MacGregor from Bullseye.

The early glasses in use were John Mansville marbles which Nick Labino brought to the Toledo workshops in '62. "Brutish and short", but they could be melted and they were the mainstay for a number of years before other cullets like Keystone and Gabbert found their way into school shops. No one really realized that Gabbert was the collator of the W.Va factories.

Why the W.Va factories were never considered as a knowledge source by the Littleton/Labino workshops to me was a strange arrogance of an existing resource or I at least think that now. It took a long time to realize that these guys knew an awful lot about making glass but since thrust in the schools at the time was ART, one person/ one piece, it wasn't going to be the case that the schools might ask for help. Even as Joel Phillip Myers who designed for Blenko became acceptable in the collegiate scene, you didn't talk about Blenko.

By the mid '70's there were more than a few of us making our own glasses but it was a minority. Private studios were coming on- the schools had great disdain for them and largely turned their backs back on that branch of the tree. When we issued the invitations for the Hot Glass Information Exchange in 1977 ( I think) Those invitations went to every school. Only Andy Billici took it seriously at Alfred and submitted a paper. Marvin came as well but then Bingham threw him out since he did not have a contributing paper for admission. There were no other schools.

We were still having issues nationally with standards. In '74, Bullseye made a 90 expansion and upstart Uroborus made the system 96 stuff which was really a 94.1. Those two shops waged war right up until the big mess five years back with the EPA.

The bulk of the german color rods had a high enough lead content that the mismatch with the glasses in use was not an issue unless you diamond sawed the work piece. Then it blew up. The yellows and reds would never fit since they had no lead in them. They were mostly about an 84 expansion

Spruce Pine originally made the first pelletized ( sometimes) batch back I think as far as 82. The first formula had too much lithium in it and it ate liners alive ( It was a 93) so Nick dialed back and the '87 became the baby elephant in the room which would outgrow everything. Lots of people don't know that Spruce pine offers more than one pelletized batch. Since the numbers are supposed to mean something, 87 is an English and Turner Calc of the formula. If you measure it, assuming a start point of 19C ending at 300C, a 4.000 length of a rod should expand to 96. Appen does a better job, but Hey..

I'm no expert on the genesis of the 104's. It seems to me it was an Italian standard pushed by Effetre. Bright colors, really soft but lampworked only. The big American thrust was on furnace work.
I'd be happy to hear any additions to that set of recollections. I have gotten tired of typing so now I'm moving to severe editing which isn't good.
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Old 11-17-2020, 05:00 PM
Josh Bernbaum Josh Bernbaum is offline
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I didn't find the bit of work I did years ago with blowing bullseye to be that challenging to work with. I also, after about 3 days, got pretty used to the 103/104 LEC clear and colors they melted in Japan when I taught a class at Aya Glass Studio there. I'm most familiar with the feel of the 96's of course, but I think that melting so many of my own colors over the years has helped me to expect differences in workability and just try to adapt to those with each different melt as much as possible. And in that sense, workability is determined by more than just the resulting expansion number but also by what ingredients are in the mix. I try to make the colors I melt fit Spruce Pine that I use for my clear, but if I were mixing my own clear I don't know if I'd stick with the 96 LEC if I didn't have to. Just a couple of my thoughts on the matter. I'm also glad though to never have had the pleasure of trying to work with the John Mansville marbles. My guess is I'd have trouble getting used to that.
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Old 11-17-2020, 06:17 PM
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Believing in physics is such a great place to start.
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Old 11-17-2020, 09:36 PM
Nick Delmatto Nick Delmatto is offline
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Quote:
Originally Posted by Shawn Everette View Post
It's most likely a result of manufacturers creating a base glass for specific applications. 90 is a great fusing glass, but garbage to blow. 96, depending on source, can be a good for fusing or blowing, but rarely great for both. 104 was designed for lampworking when you still had to pump the bellows yourself. There are always exceptions, but that's probably it in a nutshell.
With 50 years now at this, I've gone through Fenton Cullet at Kent State, factory batch formulas, Spruce Pine batch, and now for the last 12 years - factory cullet with a COE 89 (lifetime supply), mixing my own colors plus some Bullseye. It sometimes takes more reheats to get things melted in, but it's not garbage. I'm used to it & know how to treat it & it's forgiving & durable. That's good enough for me.
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Old 11-18-2020, 11:53 AM
Shawn Everette Shawn Everette is offline
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I haven't had a ton of experience with it, but I found it to be short, yellow, and easily corded; all things that I don't look for in good glass. The 90 stuff from spruce might be better, but the cuttoffs from bullseye are probably not the answer for most studios. Not to mention, unless you're making your own color, the factory available stuff is not dense enough for most applications. People like Petrovic make amazing things with it, but I'd move to batch way before using that cullet again.
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Old 11-18-2020, 11:15 PM
Nick Delmatto Nick Delmatto is offline
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My 89-90 cullet is neither yellow or cordy. I make paperweights with it. So, to call all 90 cullet as garbage isn't correct. You had crappy stuff that happened to be 90 COE.
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Old 11-19-2020, 07:52 AM
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back with the original question:

The primary makers of high expansion glass have been considered to be Effetre and Lauscha. In both of the companies, color was the primary consideration and every time you add something to a glass, it changes the expansion. It is the case in both companies that they make a line of glass with some being incompatible with others. I've measured as much as 6 points difference in both companies. If the glasses are highly leaded , and many are, there is tolerance for mismatch as long as you don't break the surface tension and saw it. The same conditions exist for German color rods that cannot have cadmium in them since cadmium and lead produce vile colors. So, the bright reds and yellows need a very specific clear.

The thing about cullet from the past worth remembering is that no one got rid of it at Gabbert because they were in love with it.
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Old 11-19-2020, 07:56 AM
Shawn Everette Shawn Everette is offline
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Do you mind sharing your cullet source? Cause the only one I'm aware of is bullseye, and it's garbage.
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