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-   -   Origin of COE as compatibility measure in studio glass (http://talk.craftweb.com/showthread.php?t=3397)

Lani McGregor 03-28-2005 01:50 PM

Origin of COE as compatibility measure in studio glass
 
Henry (you up yet?),

Dan tells me that you guys never talked about COE in the '60s in Madison.

He also sez that he thinks Harvey was (maybe) the first to import the German color bars, but he also never remembers hearing about COE in relation to those.

Where did this COE thing first come into studio glass? Specifically as it relates to compatibility? Any recollection?

-Lani

Henry Halem 03-28-2005 04:52 PM

Where, When and Who?
 
Harvey? not a chance. Dan should remember Barber was doing work with batch at Madison when we were there. Just got off the phone with Fritz and he believes it was probably Chihuly in about 67-68 that brought back color bars from Germany. Fritz knew about COE in 65 in Iowa and then when he got to Madison did work there with Barber on making glasses using The Schole's book Modern Glass Practice as the bible along with Weyl's book. Barber was the real whiz with the glass calculation though. He, Barber may have been doing glass calc. prior to 65 but we have no way of knowing as he's dropped off the face of the earth. Barber was doing his batching in 68 when I was there. So there really is no definitive answer to your question. A bottle of single malt might help me in doing more research though.

Lani McGregor 03-28-2005 06:27 PM

Quote:

Originally posted by Henry Halem
Harvey? not a chance. Dan should remember Barber was doing work with batch at Madison when we were there.
Yes, Dan still has those brain cells. And how could we forget Barber? He was production manager here for years. Bullseye’s own Raymond Babbitt.
Quote:

Barber was the real whiz with the glass calculation though. He, Barber may have been doing glass calc. prior to 65 but we have no way of knowing as he's dropped off the face of the earth.
Now, now, be kind. Portland, Oregon (where Mr B still babbles) is not “off-the-face-of-the-earth.” I have it on good authority that it is three ‘burbs better than “Bum**** Nowhere”.
Quote:

Barber was doing his batching in 68 when I was there. So there really is no definitive answer to your question. A bottle of single malt might help me in doing more research though.
Do you want that with a side of Jerk sauce or neat?

Seriously, there must be records – somewhere – as to when the color bars started being schlepped according to COE. Do you have any old product catalogues? Anyone else? Or are they all in Marvin’s attic?

Pete VanderLaan 03-28-2005 10:18 PM

Robert Held made clear reference to C.O.E. in the '67 NCECA papers he did on phosphate opals. Dudley Gibberson was also referring to it in 67. I do think Fritz was Dudleys source and inspiration.. Paul Manners did his Custom Made to Fit article for Al Lewis's old magazine but it was always referred to as Linear expansion Co-efficient (L.E.C.) which is much more correct. It also appears in Morey and Scholes as Henry suggested. Dan was the first I recall making the suggestion that viscosity was explaining a lot about fit although Nick Labino was totally tuned into it from the getgo. I wish I still did single malts.

Dale did not bring kugler in until '73 actually and talked Benheim into handling it. Then Littleton got it and started selling it and Benheim returned it all in disgust. I first saw it when John Bingham was carrying it around in a mailing tube he brought from Orrefors. John had been a student at Goddard with Billy Happel and had spent a summer at Orrefors. That was in 1971, considerably earlier than Dale's effort to supply the RISD Students. If you'll remember RISD had that catalog with the melt samples and the barrels of SODA and LIME on the cover. That was '73.

No one actively talked about C.O.E. then. It was like this magic Isotoner stuff where "One size fits all"....except for the bright Reds and yellows, and all of those awful hotdog colors which fit nothing.

Henry Halem 03-28-2005 10:54 PM

I have a vague recollection of Joel Myers having Kugler bars earlier than 73 but I couldn't swear to it. I'll try and contact him to find out. It would be intereresting to try and find out who did actually bring them in first.

Rick Sherbert 03-28-2005 11:20 PM

I sat with Fritz and Kent Ipsen a few years back at VCU and got s-faced on some good whiskey and listened to them tell stories and wishing I had a tape recorder. The old timers aren't going to be around forever and it would be really nice to have a record (even anecdotal) of what happened in the early days, like when did Kugler arrive, who brought it in and who really did throw the trout into the Penland furnace....

Tom Littleton 03-29-2005 12:15 AM

kugler
 
The story I always heard was that Kugler came to the US when David Hopper brought it back from Germany and got C & R Loo to import & sell it. The only thing I'm certain of is that HKL got into the business of importing and selling it as early as 81 and certainly was doing so in 83. I'd have to ask him if he brought any back for his own use before then. I think he was back and forth to Europe almost every year or so during the late 60s and 70s. He spent alot of time in Frauenau and it's not all that far from where Herr Kugler was.

I never heard of Benhein selling Kugler. They did sell Zimmerman and gave up after Olympic got some. However, at the time, one of the people at Benhiem also told me that they had serious safety concerns about the Zimmerman.

Durk Valkema 03-29-2005 01:13 AM

Concerning Kugler colour bars I remember dragging loads over in January '68 when Sybren Valkema was the Visiting professor in Glass at Madison teaching "European techniques" and introducing tricks like uberfang and underfang with colour bars among other tricks.
Conpatibility with the e-glass was an issue, Harvey was melting a batch from Erwin in his own shop that worked better.

03-29-2005 01:35 AM

This is like a trip down memory lane! I know we had our hands on some Kugler as early as '70 or '71. I don't know if we were getting it sent directly from Germany or from some other source. CRLoo was the earlist supplier that I can remember. I know there were times when we got a bulk order together with the University students and got straight from the factory. I think I still have a few chunks with those really old labels.
David Hopper was the first person I saw blow glass who knew what he was doing. We were just messing around until then.
I know Harvey had lots of Kugler around his shop and made pick up cups in '79. We certainly knew about fit and expansion before that and did lots of calculations to increase and decrease "LEC". Paul Manners paper was biblical material.

Henry Halem 03-29-2005 08:02 AM

The imperfection of memory
 
First of all it's Bendheim non Benheim. Kugler bars came here before Loo ever started importing. The only way you could get it was to order directly. You had to go to the Customs office and pick it up. If the person in customs didn't like you for some reason they made you pay 7% duty if you didn't look like a hippy you could just sign for it.
Durk, that batch that Erwin melted at Harvey's was a black and a white. Erwin made the most fantastic pieces of German expressionistic glass I ever saw. As I recall the glass was very and I mean very soft but for a reason, it all devitrified into a slimmy mass. David Hopper worked with Erwin in Germany and did make some fantastic work. I remember his white scultural pieces very much influenced by Erwin. In my estimation Erwin was a very important figure in the American glass studio movement and is not given enough credit. I will be in Penland this summer and if HKL is up to it I will go and pay him a visit and of course try and jog his memory of that time. Of course TL can do that now if cares to.

Lani McGregor 03-29-2005 09:02 AM

Hey, the dog's running off with my thread ...
 
What I’m still digging for - more even than the origin of Kugler importation - is where specifically in time COE/LEC came into the studio glass vocabulary as a term synonymous with compatibility.

Were the early Kugler bars referred to by a specific LEC? Were they marketed that way by C&R Loo et al?

When Hugh mentions knowing about fit and expansion, how was that measured? Theoretically, by calculation? Measured with a dilatometer? Or a number provided by a manufacturer? Were the early clear studio batches designed to fit Kugler? If so, how was that fit measured?

Was SPB the first commercially available batch in the US studio glass scene? What was it designed to fit? How was the "fit" measured?

In Europe what had Kugler been designed to fit?

To my knowledge, the American factories (Fenton etc) never used color bars, but melted their own color. How did/do they measure the fit/mismatch of their color?

Anyone know the date/issue of the Manners article in what Pete calls “Al Lewis’s old magazine” – was that “Studio”?

Incredible what that first cup of coffee will do to you.

Jon Myers 03-29-2005 10:37 AM

I love this kind of thread.... I heard that Spruce was formulated to fit K61(white), is that true? As I'm reading this I'm thinking we're missing the boat by not having an organized oral history of the studio movement early days while we still can. Since we have the attention of a lot of smart folks here online we should put together a set interview questions and interviewees.
Some of the people who were instrumental were not book writers so their footprints will fade as the people who walked by, and directly behind them die off. One of the neat things about the internet is that there is a reader of this board within 100 miles of almost every major glass figure I can think of (which is not that many as I an new to this and don't know who did what 20 years ago hence the need for something like this(for me at least)) I would be willing to travel in the wintertime to work on something like this and I'd imagine that there are others who would like to get in on the fun....I'd love to have an excuse to talk to some of these folks....

Pete VanderLaan 03-29-2005 11:10 AM

Scholes made the only presentation that the studio movement used. Books like Morey simply weren't being read. The early Kugler had NO references to expansion factors. It just magically fit. Expansion really entered the mainstream as something to measure after Paul's article. Again, Nick would always say he didn't know why high lead glasses had such tolerance, just that they did. Once Nick made the initial SP batch formula ( I believe SP92), expansion and compatibility became common in discussions in private shops, but not much in the schools that continued to say things like "It's OK to put the purple over the yellow but not the yellow over the Purple". In any of my time at Pilchuck- 77-78 it was never mentioned once. but the private shops that made their own color knew. I don't think at the time that private shops were much into casting and so the annealing- viscosity issues were not on the table. The Manners article really brought it upfront. These days if I talk about measuring viscosity, people's eyes glaze over.

Sorry about Bendheim. I really couldn't remember the spelling and tried it both ways. I do remember them having color rods way before Loo though. If it was Zimmermann, it's possible. At that time Zimmermann was flakey, cordy and sometimes stone ridden. We said it had character. I always liked their colors better than Klaus's.

I brought a load in once thru a friend stationed in Oberamagau and he was to ship us about 40 KG. His garage caught fire and the whole thing turned into one big block which he shipped us anyway. We would whack off chunks with a big chisel. I remember the airfreight and customs part too.

But Lani, why the interest outside of the fact that you guys have a proprietary interest and don't really think L.E.C. is all that critical compared to viscosity- which may be because you tend to work with big long flat sheets that can really drag themselves around a lot.

Henry Halem 03-29-2005 01:52 PM

Quote:

Originally posted by Jon Myers
I love this kind of thread.... I heard that Spruce was formulated to fit K61(white), is that true?
Not true!

Lani McGregor 03-29-2005 02:00 PM

Quote:

Originally posted by Pete VanderLaan
The early Kugler had NO references to expansion factors. It just magically fit.
Magic? During the time when Hopper visited the Eisch factory in 1969 (per David this AM) they were testing for compatibility two ways:

- the thread pull test (which, as we all know, measures the differences between glasses based on the combined factors of their viscosity and their expansion)

- a softening point test (which, not to insult anyone’s intelligence here, is also an indicator of viscosity).

I’d assume that Kugler - located so close to Eisch - if he was testing for compatibility at all, was using similar methods. But that’s an assumption. Maybe he was using magic. As you state, it appears that he was NOT using LEC.

Quote:


Expansion really entered the mainstream as something to measure after Paul's article.

Again, I’d love to find this article. Got a date/issue number?


Quote:


But Lani, why the interest outside of the fact that you guys have a proprietary interest and don't really think L.E.C. is all that critical compared to viscosity- which may be because you tend to work with big long flat sheets that can really drag themselves around a lot.

I’m not sure what you mean by “proprietary interest”. Can you explain?

And I’m also not real clear on what “big long flat sheets” have to do with it.

As to our not thinking LEC is critical, that’s NOT what Dan’s been saying. His sole argument is that it’s only half the story and has oddly become a standard with the inherent problems of all over-simplifications.

Why the interest?

A) material science/history curiosity

B) having to deal with the confusion/suspicion that continually results (what you call “eyes glazing over”) in trying to insert viscosity into the compatibility discussion.

C) marital discord: the other day as Dan was banging his head yet again against the kitchen wall trying to clarify LEC/viscosity relationships to my dull (and hugely unscientific) brain, I shrieked back at him in my best Fishwife voice “Aren’t you going to feel like an asshole if it turns out that this problem of equating the COE with compatibility really got going when you and that lame-ass ex-partner of yours wrote that stupid book in ’83 and suddenly [at least in our corner of the market] it was all “COE 90 glass and COE 86 glass” blah blah blah. Now that I’m hearing it’s all Paul Manners’ fault, I just need to find Mrs Manners and see whether LEC screwed up her marriage too.

So, where’s this article?

Steven O'Day 03-29-2005 02:00 PM

Bendheim carried Kügler before Loo, but had a falling out about business practices. They picked up Zimmerman somewhat later, but Zimmerman went through a period of really awful quality control which was straightened out. They were also carrying Wiesenthalhütte which I believe at that time was made primarily for pressing jewels and other things and was not really made to be compatible. Eventually Bendheim was just not too interested in hassling with color anymore and gave it up.

I think the Swedish factories use the bars, but I don't know if this is a recent thing or not.

Durk Valkema 03-29-2005 03:20 PM

Harvey and Erwin played around with the black and white while Erwin was there autumn '67. I distinctly remember clear glass in Harvey's shop spring '68, I will check.
Most factories' in Europe melted there own colours and made bars on the side for own use (at Orrefors Sven Palquist 'Colora" series in fuga technique 1953, and Gunnar Cyrén "Pop" goblets from 1966) but used Kugler, Zimmerman and others as well and simply adjusted the clear base to fit. Leerdam used to make bars for there own use. Donated the remaining 3-ton of it to the school later on.
I will check my father's notes to find out more and talk with the Leerdam chemist. The big change in Leerdam came after the war when the tableware production was automated and crystal production reduced. They did have a small test/colour furnace in the back of the crystal furnace though. This is where my father experimented with his students of the glass school (1943-52) and where he learned glass blowing himself.
As to compatibility, the early morning test was the thread pull, followed by the cylinder cut and tested after it annealed on the belt for 3 hours. For precise dating I will have to do some research.

Lani McGregor 03-29-2005 03:37 PM

So - Hi, Durk! - was a connection between LEC and compatibility of glasses part of the discussion in European glass factories (then or now?) to your knowledge?

Pete VanderLaan 03-29-2005 06:53 PM

well, I still have the article and I will copy it for you. I will have to find it however but I know which room it is in. It does make a gross error in that Paul used the English and Turner numbers which have really done a very good job of standing the test of time BUT he then included the Winkelmann and Schott numbers for colorants as well. Those numbers were created for the enamelling industry and utilized an entirely different range in which to measure the expansions. They comedy of errors was compounded by Glassnotes using those numbers as well and they don't have anything to do with the real world. Simply put, there are no values for metallic oxides that are used as colorants. Industry never cared since they never planned to case colors with clear as a production item.

I really think that L.E.C. works so well for glass blowers that the viscosity issues have just about never concerned them. Not many people make the connection between viscosity and annealing ranges in thinner ware. In casting, you guys have to anneal forever , only to open the kiln and find the piece cracked which tends to make one ponder the issues at hand a good deal more. There is a lot going on. Glassblowers really get instant gratification and when things don't fit, usually you know pretty quickly. In that capacity, I don't think that Dan's observations about viscosity being the flip side of the coin will ever gain much traction. That is not the same as saying that the observations aren't correct, I think they are.

Where I think the problem lies, is in the gross generalization that such things as "96" guarantee you a clear blue sky and great sailing. I was just talking to Henry about a zinc sulphide cad sel red that is in the last edition of GlassNotes. It is a very nice red, but the L.E.C. is about 114. Cad sels really have to have at least three percent zinc in them to work well, or at least I've never seen one work with less zinc than that. That in itself is OK but if you want to make that glass color into a 96 as well, it's going to be kind of stiff to work while the clear is fairly runny. That tells me something about the likelyhood of mixing those glasses in really thick pieces as being problematic. Theyu do however work well in blown ware.

As to Mrs Manners, She and Paul long ago divorced and the last time I had heard a thing from Paul, he had quit glass and was teaching kindergarden and playing beach volleyball.. Then he vanished entirely. Anyone knowing his whereabouts, please tell me. I haven't heard a word since 1986.

Pete VanderLaan 03-29-2005 07:19 PM

Glass Art Magazine August 1973. Great issue. the article talks about matching "Drykiln Crystal A" cullet. Also a very nice picture of Kathie Bunnell and an ad for bullseye glass selling opal colors and clear colors for 1.85 sq ft. Also Bob Biniarz teaching a summer class at the Archie Bray Foundation.

Lani McGregor 03-29-2005 07:43 PM

Quote:

Originally posted by Pete VanderLaan
Glass Art Magazine August 1973. ...an ad for bullseye glass selling opal colors and clear colors for 1.85 sq ft...
OK, Pete, now we are into magic: Bullseye wasn't founded until 1974.

Tom Littleton 03-29-2005 11:44 PM

HKL
 
Henry,
HKL won't get back from Florida for at least a couple more days. He's had a fun winter trying to rebuild his apt and gallery that the hurricanes blew away but now my mom wants to get back to NC. Soo.. It'll be a little while fore I can ask him anything.

As for the original formulations of the labino formula othewise known as sp batch, and again this is as I remember, Nick gave us the original formula as a "chemical" formula and not a list of materials. We had to convert it to a list of materials and we had our first test melt run at Penland. Bill Worchester was there at the time and It did not melt well. We got a different mesh silica and added the Lithium at Labino's suggestion. With those changes, we ended up with the formula now known as the 92. The 92 turned out to be less than Ideal. Sooo.. The expansion was lowered and I always thought we had tried to match the Kugler 61 as it was the most popular color. However, I was not the one that was actually doing the work. This new batch formula had a theoretical expansion of 87 so that is what we called it.

Henry Halem 03-30-2005 08:03 AM

The original SP had very high Lithia as you say suggested by Nick but because the viscosity was so low it ate everyones tanks and pots like pak man. You reduced the lithia and voila SP87.

Robert Mickelsen 03-30-2005 09:02 AM

Quote:

Glassblowers really get instant gratification and when things don't fit, usually you know pretty quickly. In that capacity, I don't think that Dan's observations about viscosity being the flip side of the coin will ever gain much traction.
Pete, as a flameworker who is accustomed to much more instant gratification than even glassblowers get I want to respectfully disagree here. I am *very* interested in this thread and am following it closely. There have been issues with borosilicate glass fits that justify the validity of viscosity as a factor in fit, even in low-expansion borosilicate glass. For instance, there is an opal green that is notorious for crackling when incased. But the measured LEC is dead-on that of clear boro glass. Why doesn't it fit? The only answer, and what I have been telling students for years myself, has to be variations in the viscosity curve of each glass.

Fascinating discussion folks. Please continue...

Bruce Troeh 03-30-2005 09:08 AM

origin of COE
 
While Iowa State still has the glass facility it no longer offers glassblowing except through the Glasblowers Guild. I started in 1977 learnign (sp) about formulating batch and calculating COE with Dr. David Martin. At the time I remember one of the grad students had purchased a box of kugler color I dearly wanted to use. Our batch was 111 - 113 COE. I do remeber a few broken pieces.
I've got a box of kugler to play with now but I'm using 104 so it still sits. BTW. Bruce

Tom Littleton 03-30-2005 09:16 AM

Henry,
That is not correct. Where did you get your info?

I have to say we got lucky with a short learning curve but we did have Nick's help. The first stuff that got melted at Penland was made to the orginal formula and which had no lithium. As I remember, the stuff was so hard to melt it got cooked at high temp for 24-36 hours perhaps the source of you stories. We were trying a relatively large grain local sand. We tried screening that sand to get a smaller grain but that didn't work. I remember only two people got some of those first runs. We tried changing the source of the sand and added the lithium at the same time and by the way it was the maximum amount suggested. We should have tried changing one thing at a time and used less lithium and then increasing it in a series of tests but that was not done. The result was the 92. We only took out a little soda to make the 87.

Pete VanderLaan 03-30-2005 09:43 AM

Quote:

Originally posted by Lani McGregor
OK, Pete, now we are into magic: Bullseye wasn't founded until 1974.
well, you are right. I actually included the items from a few other issues that popped up just for effect. The price on the glass was right though. I do have the ad announcing the grand opening of bullseye.
40th anniversary indeed!

Dave Bross 03-30-2005 09:54 AM

Wow! spectacular thread! Do continue!

If anyone has that book that HKL did in the late sixties there is a lot of discussion of what went on with Erwin at the factory as regards melts. I read the book a few years back in the Seattle library so I don't have a copy to reference now.

Tom,

Are there any other reasons besides expense of material that you wished you had used less lithium?

Durk Valkema 03-30-2005 09:54 AM

History
 
Just spoke with my friend the chemist at the Leerdam plant.
In his memory Kugler colours where used in the Crystal production all the time. Kugler was asked to make a melt to fit but if it did not the clear was adjusted.

It was tested by production doing the ring test.
The lab used the "method Dr. Patmos". Dr. Patmos worked for Philips and developed a test where a standard clear was welded to the glass to test. After annealing the weld was cut and polished and viewed through a micro polariscope to measure the tension.
Necessary for the developments of all the different light systems Philips developed.
This is all pre 1950.
His remark on the COE, LEC and viscosity was very practical, to my friend its all very theoretical if you know the LEC you know the COE and for him viscosity has to do with machine speed. Than again he is all about container glass. Density of 2.5 at room temperature but only 2.25 at 1400 C (2552F)
Batch calculations with expansion is only practical empirical info, measure and you will know.

Pete VanderLaan 03-30-2005 09:55 AM

Quote:

Originally posted by Robert Mickelsen
glass. For instance, there is an opal green that is notorious for crackling when incased. But the measured LEC is dead-on that of clear boro glass. Why doesn't it fit?
Fascinating discussion folks. Please continue...

When you say it is dead on, who measured it and how. Is it a pull test? I simply do not trust pull tests in opal/clear matches as even remotely reliable. They only work in formulas of similar composition. It would require dilatometry or a ring or trident seal test to get accuracy here. Chrome glasses are refractory in nature and the problem is compounded by opacity. If it is a boro supplier, I have so far not been overwhelmed by the current group of suppliers being terribly thorough. It's a comparatively young industry when it comes to color and actual batching of colors.

Lani McGregor 03-30-2005 10:45 AM

Quote:

Originally posted by Pete VanderLaan
I really think that L.E.C. works so well for glass blowers that the viscosity issues have just about never concerned them.
Pete, IMO what works well for glass blowers is glass blowing. Not LEC. I happen to know three glassblowers who started a glass factory and found out – while trying to fit different colored glasses together in streaky sheets – that after sending in numerous tests to laboratories (late ‘70s) they could only make the glasses match by INCREASING the difference in their COEs (0-300C). Everything they thought they knew about expansion and fitting colored glass had only taken them in the wrong direction.

Quote:

Where I think the problem lies, is in the gross generalization that such things as "96" guarantee you a clear blue sky and great sailing.
Exactly. COE is half of it. Viscosity is the other half. One without the other is certainly a place to start, but is misleading. Matching COEs only works if the base compositions are the same or very similar. Who can make a broad color palette with only one base composition? Bullseye has at least five different base compositions for its line of colored glass. If we made the expansions the same on each of these they’d be grossly incompatible.

At the time BE developed its Tested Compatible line Boyce (ever the salesman) liked to call it “90 COE” and, IMO, intended to take over the kiln world at that “expansion”. Dan was never completely comfortable with the corruption of glass science entailed in that kind of marketing. Of course they could have called the glass “990 AP” instead of “90 COE” and been equally right – and equally wrong. For accuracy, it would have been more accurate to call it a 90/990 glass.

I’m just curious as to where the COE as a synonym for compatibility first entered the marketplace and hot shop. When did color bars or batch start to be listed/distributed in those terms?

And I’m talking measured (i.e. at 0-300C) not theoretical or calculated COE. Lots of people were doing calculations. But to our knowledge the practical testing done in factories on a daily basis has always measured the “fit” between glasses, i.e, the combination of expansion and viscosity – NOT the COE.

When did SPB first list a measured COE? I’m pretty sure that what Tom and Henry are talking about in terms of Labino’s formula is calculation.

Robert Mickelsen 03-30-2005 11:24 AM

Quote:

Originally posted by Pete VanderLaan
When you say it is dead on, who measured it and how. Is it a pull test? I simply do not trust pull tests in opal/clear matches as even remotely reliable. They only work in formulas of similar composition. It would require dilatometry or a ring or trident seal test to get accuracy here. Chrome glasses are refractory in nature and the problem is compounded by opacity. If it is a boro supplier, I have so far not been overwhelmed by the current group of suppliers being terribly thorough. It's a comparatively young industry when it comes to color and actual batching of colors.
I know the green was tested on a dilatometer and was on the money. The color manufacturers have tried for years to solve the problem to no avail. You are absolutely correct in what you say about the present group of suppliers.

Lani McGregor 03-30-2005 12:18 PM

Quote:

Originally posted by Pete VanderLaan
When you say it is dead on, who measured it and how. Is it a pull test? I simply do not trust pull tests in opal/clear matches as even remotely reliable. They only work in formulas of similar composition. It would require dilatometry or a ring or trident seal test to get accuracy here.
Just so we're all straight on what's being measured:

a DILATOMETER is used to measure the expansion, e.g. COE(0-300C) or “LEC”. This is the measurement of an isolated glass.

The following three tests measure the combined effect of expansion AND viscosity on two different glasses:

RING TEST

TRIDENT SEAL TEST

BULLSEYE’S CHIP/BAR TEST

The PULL TEST is also a rough measure of the combined effect of expansion and viscosity on two different glasses, BUT in our factory experience it is very frequently unreliable due to on the skill level (or lack thereof) of the person performing the test.

Pete VanderLaan 03-30-2005 12:21 PM

Quote:

Originally posted by Lani McGregor
terms?

And I’m talking measured (i.e. at 0-300C) not theoretical or calculated COE. Lots of people were doing calculations. But to our knowledge the practical testing done in factories on a daily basis has always measured the “fit” between glasses, i.e, the combination of expansion and viscosity – NOT the COE.
*************************************
When did SPB first list a measured COE? I’m pretty sure that what Tom and Henry are talking about in terms of Labino’s formula is calculation.


Actually you have hit on the first point of confusion. How about 17C-300C instead. When I did the work at Los Alamos labs with this, we started at 0C just like the ASTM standard would have suggested. Nothing made real world sense. Once I shifted to 17C as a start point, things looked right. 17C is of course the temperature at which lab workers are comfortable while wearing white coats. I have to be very careful when I'm measuring four inch rods for expansion that the start temperature is consistent. In summer, it easily goes up to 23C so I need a cooling bath for the canes and dilatometer.

The labino stuff is calculation and it is consistent with the E&T numbers if run up to 250C ( I think). E&T did not originally go to 300C and that's why those numbers have never made real world sense. It seems to me it was either 250C or 225C. I cannot recall right now and I don't want to look it up.

When Croucher and I sat down about eight years back to talk about expansion we both felt that a 93-93.5 would have been a better standard but SP87( which is really a 96) was the elephant in the room. If we wanted to sell color that was not 45 percent lead we were going to target SP87. While Kugler just got around the fit issue by dumping lead into the glasses, we really wanted lower lead contents wherever possible and no lead if it was not critical to the glass. Kugler and company all use GLASMA 70 or 71, I forget which but it is their proprietary batch. It has a predetermined L.E.C which they add colorants to. It explains why Kugler is all over the map. John and I both made the color first, and then adjusted the glass to a 96.

I agree about the multiple formulas. I have six base glasses. I think John had seven the last time we talked. The trouble with the viscosity issue is that I can't explain it. Nick couldn't explain it. Why did lead seemingly defeat the compatibility problem up until you pierced the surface tension of the piece with a saw or a grinder? Would a high Bismuth glass do the same thing ( moot since bismuth is too expensive).

I don't think anyone listed an L.E.C. on their stick until Croucher. I never did. I advertised its expansion but never put it on the rod. I liked the parrots too much.

Maybe glassblowers are more like the tarot card of the fool. Walking towards the cliff and always the presumption that they will turn at the last minute without ever knowing the cliff was there.

Pete VanderLaan 03-30-2005 12:26 PM

Quote:

Originally posted by Robert Mickelsen
I know the green was tested on a dilatometer and was on the money. The color manufacturers have tried for years to solve the problem to no avail. You are absolutely correct in what you say about the present group of suppliers.
***************************
Is this that green that was a square stick and came from the phillips plant in NY along with the opaque white stick about three years back? Secondly , who did the dilatometry tests? Do you really know firsthand that it was tested? That's what I mean about the suppliers.

Lani McGregor 03-30-2005 12:51 PM

Quote:

Originally posted by Pete VanderLaan
John and I both made the color first, and then adjusted the glass to a 96.

Pete, I’d still argue that you weren’t adjusting to a 96 COE, you were adjusting to fit SP87.

Do all glasses with a 96 COE fit SP87?

And you think viscosity is confusing?

BTW what’s the AP of SP87?

Quote:

Originally posted by Pete VanderLaan
Why did lead seemingly defeat the compatibility problem up until you pierced the surface tension of the piece with a saw or a grinder?

I don’t understand how the compatibility problem is even “seemingly” defeated if it’s only compatible until you cut into it.

Steven O'Day 03-30-2005 12:55 PM

In the mid 80's Therese LaHai was at CR Loo and wanted to try and figure out the in-compatability problem. She had the base glasses and colors tested and published the COE numbers in the catalog as a rough guide. I don't remember any talk of viscosity. I think at the supplier level before this it was caveat emptor, the numbers used were the ones from the manufacturers or the E & T theoretical.

Pete VanderLaan 03-30-2005 01:06 PM

Quote:

Originally posted by Lani McGregor
Pete, I’d still argue that you weren’t adjusting to a 96 COE, you were adjusting to fit SP87.

Do all glasses with a 96 COE fit SP87?

And you think viscosity is confusing?

BTW what’s the AP of SP87?



I don’t understand how the compatibility problem is even “seemingly” defeated if it’s only compatible until you cut into it.

*********************
That's why I said that the viscosity issue has never gained any traction. Glassblowers seem to be content with the notion that they can't cut and grind their work made with a lot of german color rods. It's bizarre but people seem very accepting of it. I don't disagree with you. It would seem as long as it doesn't actually explode, it's OK. How many people have you seen who still try to use bright canary yellow opal from Kugler. It doesn't fit anything on the planet. It still sells and if you don't grind it, it holds together for some time if you use cullets that are nearer to a 90.

I have been a vocal minority for a loooong time that the glass made in the 70's and 80's well may be the cullet of this century in due time. It's like pushing back the tide. I am simply stating the way I perceive things to be.

As to all glasses that have 96 C.O.E. fitting Sp87, no I don't think that but I think it based on the thickness of the two glasses that are present. I make opals at 96 that saw and grind with SP87 just fine if they are under one inch thick. Go over that and they don't fit. Why? my hunch is annealing range, not point.

You live in a casting world where thickness is a day to day issue. Things crack. They don't crack in blownware and the schools have absolutely no technical interest in this crap at all anymore. They have all adopted Dale's out of sight out of mind approach to broken glass.

As to the argument about what we were aiming at, I measure my glasses as a 96 on a dilatometer. I do that because I can usually measure SP87 as a 96 or very close. I make the number my target these days. I don't actually have any SP87 in the building right now and haven't for about a year. If SP varies, and it does occasionally, I simply can't try to follow the day to day vaguries of the soap opera. I need to be within 1.5 ten thousandths., that's all.

The annealing RANGE of SP87 is about 890 to 945 depending on thickness and how fast you want to anneal it. I put away large grinding blanks that are thick at 995 for about an hour before dropping to 940. If I don't, I have really cracking issues on grinding them or I have to anneal them at 940 for way to long a time.

When Croucher and I made our presentations at Corning back in 2001, Frank Wooley, senior melt engineer at Corning was there and got into the Q &A very actively. I made the assertion that a substantial number of "Checks" in pieces were really being mistaken for incompatibility when they were actually annealing problems. Frank became very animated in agreement. We talked about it for some time.

Tom Littleton 03-30-2005 01:39 PM

Dave,
Expense is the biggest reason for not wanting to use a relatively large proportion of lithium but it also has a bad rep as a very aggrssive flux. My feeling is though (without actual data to back me up) that by the time you replace the fluxing action of the lithium with something else whatever you come up with will be just as corrosive.

Lani,
I can't remember when I started putting a measured COE in the sales material. I think fairly recently and likely when everyone else started talking about COEs and stuff and started to look at the 87 as a standard. No more than 8-10 years at the most but I'd have to check and I didn't always keep good records of when I made changes. It seems like it became more of an issue when the Dichroics came out and people wanted to use them in their furnace worked glass and the 90 standard stuff would not work with the SP 87. And likely after Pete learned how to build and operate a a dilatometer.

Lani McGregor 03-30-2005 02:04 PM

Quote:

Originally posted by Tom Littleton

Lani,
I can't remember when I started putting a measured COE in the sales material. I think fairly recently and likely when everyone else started talking about COEs and stuff and started to look at the 87 as a standard. No more than 8-10 years at the most but I'd have to check and I didn't always keep good records of when I made changes. It seems like it became more of an issue when the Dichroics came out and people wanted to use them in their furnace worked glass and the 90 standard stuff would not work with the SP 87. And likely after Pete learned how to build and operate a a dilatometer.

Tom, thanks. This is the input I was looking for. COE as a measure of compatibility seems to have showed up in the vocabulary of studio glass very recently (certainly quite a while after BE published Glass Fusing Book One in 1983 and our side of the market – i.e. kilnworkers - grabbed the “shorthand” tag of “90 fits 90” with all its half-accuracies and commercial agenda).

I'm not saying that the batch or color manufacturers are wrong to provide COE info, just that users think this equates to compatibility when any colored glass maker knows it doesn't.

Tom, do you provide an Annealing Point for SP 87? (Not the annealing range – the AP as determined by the ASTM test)? A softening point?


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