BAD CAT | Bullseye Glass Co. | Bullseye Glass Co

BAD CAT

When visited in our last blog episode, Ed the Cat was sitting prettily – a word he would surely have detested – in his Chintz-y metal box on our kitchen windowsill. Dan still hasn’t managed to come up with a bone ash opal formula that’s worthy of Ed’s six ounces of dust.

What’s the hold up? It’s a color formulation problem. Ed just can’t become anything other than a red, yellow or orange glass – colors that are typically made with cadium/selenium oxides. Those of you who know a little glass chemistry will recognize them as the most ornery, irascible and unpredictable colors in any glassmaker’s palette.

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Dignified? What’s dignified about sitting around in a tin can waiting for a glass chemist to get his act together?!

Cadmium/seleniums are so ornery, in fact, that I was pretty surprised when Uroboros’s Bill Ward recently appeared on the Warm Glass bulletin board to state that “…our 90 [COE glass] was designed to be compatible with Bullseye Tested Compatible and these have been comingled successful by many artists since 1989.”[sic]

Checking out the Uroboros website, I saw the same claim “Products at the 90 COE expansion point are tested compatible with Bullseye glass”

Over the years I’d heard about problems with mixing this so-called “90 COE” glass with ours, but I’d never seen any formal testing to investigate the issue. Bill’s remark got me into gear. (Or maybe it was Ed’s peevish spirit).

Either way, Dan drove on over to our local glass retailer and picked up samples of all the Uroboros red, yellow and orange glasses that he could find on the shelves.

TRIPLE FIRES: Measuring Irascible Glass

Because cad/sels have a tendency to change their internal composition on multiple firings – as might happen with a color-bar/full fuse/slump series of firings – we expanded our testing of these glasses years ago to include what we call Triple Fires.

In a Triple Fire test the same sample of glass is fired three consecutive times to a full fuse temperature. After each firing, the test sample is cooled to room temperature and viewed for stress at the interface between the chip and the standardized base glass. If, after any one of the three firings, the chip shows stress greater than our accepted deviation of 2 degrees low to 4 degrees high, it is considered incompatible with that standard and its related glass will not be labeled Bullseye Compatible.

After we instituted Triple Fire Testing both Uroboros and Spectrum glass factories followed suit with claims of “three meticulous test firings…measured for ….COE-shift”.

But – as I’ve been ranting all these weeks – unless a glassmaker explains exactly what their testing protocol is, I’d consider the claims to be just…well…marketing.

READING THE TRIPLE FIRE TEST

I hope you’re not totally bored after all these weeks of looking at fuse test bars. Because the ones coming up here are instructive.

Of the six Uroboros samples that we purchased randomly from our local glass store, four failed our triple fire testing.

This is what they looked like through the polarimeter.

First, the good news (for users):

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UB’s 60-606.90 Grenadine Red Transparent passed the test. Against Bullseye’s base clear standard it showed to be within the acceptable range with 1/2 degree high on the first firing, 1 degree high on the second and 1/2 degree high again on the third.

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The 60-357-90 Lemon Chiffon Yellow Transparent also passed with 1/2 degree high of measurable stress on the first firing, 1.5 degrees high on the second, and 1.5 degrees high again on the third.

Then our cadmium/selenium friends started to unravel.

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The 60-608-90 Tangerine Transparent was just outside our standard range on the first firing at 5 degrees high. Then it went further out to 6 degrees high. On the third firing it went back just slightly lower at 4 degrees high.

Note that most glasses, when their chemistry alters due to more firings, will trend consistently in one direction – either going increasingly higher or increasingly lower. A glass that behaves erratically like this one usually indicates inhomogeneity within the piece of glass. But without access to the full run of glass from which this sample was taken, it’s really not possible to say for certain why it behaved this way.

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The 60-356-90 Lemon Yellow Opal was compatible to our standards on the first firing at 1 degree high. On the second firing it went over the limit at 7 degrees high. Then it shot even further out to 11 high on the third firing.

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The 60-351-90 Marigold Opal was a loss right out of the starting gate: 6 high, then 10 high, then 15 high.

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The 60-604-90 Red Opal was the biggest problem in the bunch. It came closer to matching a “96” glass than a “90” with headlights flaring at 10 high, 15 high and finally 20 high.

Of course I’m very curious to know what Uroboros uses as their testing protocol, but since Bill wouldn’t answer the question at Warm Glass, we’ve had to try to figure it out for ourselves.

As I stated on Warm Glass, I’d certainly like a dialogue between factories that would help users really understand what compatibility in our field means. But I like my discussions in public. Until we can have them here, I guess I’ll just drone on alone.

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Meanwhile, we’ve left Ed to muse on the prospect of his precarious afterlife as a cadmium/selenium jewel.

In the end, a stable cad/sel is a delicate work of art, not to be taken lightly or glossed over with vacant claims of “COE 90″ or “…the industry’s most rigorous testing”. Sometimes compatibility just isn’t so easy. But neither was Ed – and we loved him for it.

9 Responses to BAD CAT

  1. Morganica says:

    A marmalade-cream-gold streaky would be nice…

    So…how do we get from “Lemon Yellow and Grenadine Red stay within acceptable limits” to “these glasses are tested-compatible with Bullseye kilnforming glass and these are not?”

  2. Lani says:

    Sorry, Cynthia – I don’t understand the question. – Lani

  3. Morganica says:

    Oh gosh. People who ask me to write long generally wish they hadn’t. ;-) Sorry for the lack of lucidity; I just realized that I can’t hang a great new piece of glass over my office fireplace where I’ll get to see it all the time because it’s too fragile and some daggone client will probably be seduced by the close-up textures, grab it and…crrrrrk! Drat. It distracted me into deeply compressing the following train of thought:

    It would be nice if someone with great facilities for rigorously testing glass could purchase representative samples of every “COE90″ glass they could find and do the same testing you describe here. They may have already done that, in fact.

    But what would be far more useful is if they then published a report saying “the following non-Bullseye glasses remained within acceptable compatibility tolerances for one/two/three firings, and the following glasses did not, and here are the stress test photos to prove it.”

    Seems like it would be easier to do that than to build an industry-wide standard for kilnformed glass compatibility, especially if the report also had a section entitled “what this means for kilnformers.” It might, in fact, eventually result in such a standard. When I thought this through initially my statistician persona said, “Dumb idea. You can’t extrapolate findings based on one small piece of glass purchased in a single store to the output of an entire factory. What if the factory changed processes and therefore invalidated your results?”

    Then my publishiomarketeer persona (sorta like sociopolitical but more venal) took over and said, “Not if you follow the Consumer Reports method. Purchase samples from multiple stores. Include a precise description of your sampling and testing methodologies in the report. If you’re feeling journalistic, send a copy of the report (or at least the test methodologies and a list of products tested along with sample purchase dates and any production codes you found) to the manufacturers and ask them to respond with any details that might affect the results. Incorporate their feedback in the report (or that they refused to provide feedback), and publish. At that point, if the glasses are inconsistent enough to contradict your findings, that’s the manufacturer’s problem, not yours.”

    Lots more thought around the publisher’s credibility, marketing implications (could it potentially be seen as an endorsement, etc.), etc. But that’s what I meant by the question. Bullseye’s just announced that Lemon Yellow and Grenadine Red stay within acceptable compatibility limits while Lemon Yellow, Marigold (boy, that one hurts) and Red do not. I would really, really love to see a report that did the same thing for all “COE90″ glasses.

    Hmmmm. It’s an interesting enough project that I wouldn’t mind taking it on, except that my test lab at the moment consists of two sheets of sunglass material and a big flashlight. ;-)

    But I would buy such a report. Heck, I’d even buy the glass.

  4. Lani says:

    “Bullseye’s just announced that Lemon Yellow and Grenadine Red stay within acceptable compatibility limits while Lemon Yellow, Marigold (boy, that one hurts) and Red do not.” [Cynthia writes]

    Cynthia, all we’ve announced is that we found these results for these individual samples. We are in no way claiming that other samples of these glasses would or would not be compatible with the Bullseye standard.

    The ONLY predictor of compatibility is rigorous daily testing within the factory on EVERY RUN of glass. Because one sheet of a particular style of glass is compatible with the standard on one day is NO guarantee that another sheet of that same glass made on another day will be compatible.

    That’s what “Tested Compatible” means.

    At least at Bullseye. I am clueless at this point as to what it means at Uroboros.

    -Lani

  5. everseeker says:

    Cynthia, your statement “…Bullseye’s just announced that Lemon Yellow … while Lemon Yellow …” is a bit on the generic side…

    Let’s at least be … specific … about things. Otherwise, your comment makes no sense…
    It would be better to say…“Bullseye’s just announced that Lemon Chiffon Yellow Transparent and Grenadine Red Transparent stay within acceptable compatibility limits while Lemon Yellow Opal, Marigold Opal(boy, that one hurts) and Red Opal do not.”

    still, I too disagree with your premise. Lani has merely pointed out the fact that “tested compatible to Bullseye” means NOTHING if not done by Bullseye. If you intend to purchase glass from multiple sources, it is your responsibility to exercise due diligence by testing them yourself for compatibility.
    Although a home user working with 2 pieces of old polarized glasses will not get perfect results, incompatibilities like the Red Opal had could be seen by a blind man at 9000 meters

  6. Lani says:

    Everseeker, thank you.

    That IS the problem. “…’tested compatible to Bullseye’ means NOTHING if not done by Bullseye.”

    It COULD mean a lot more than it does if the manufacturer making the claim would provide:

    A) What their standard is, i.e., what base clear glass they’ve tested these samples against.

    B) What their testing procedure is.

    C) What they consider acceptable in the deviation from their standard.

    Without that information, simply claiming that “these are 90 COE glasses” and “they are tested compatible to Bullseye” is giving the user nothing – except a raffle ticket where the odds of winning are probably better than having no ticket at all. But it’s not how I’d spend my money.
    – Lani

  7. JetAge_Studio says:

    Hi Lani,

    A couple of questions:

    I was under the impression that Uroboros and Bullseye were working together, they are not? (guess I thought Uro and Spectrum were working together too….hmmm) Perhaps this is one contributor to the compatablility confusion (at least with me if nothing else). If one company (Uro) says they are making glass compatable to a company who sets a standard (Bullseye for instance), doesn’t the “standard setting” company get to police the other company so they COULD make that claim? Yes/No? I’m not sure how all that works.

    Another question, In your above tests, you mention “degrees of stress”, how IS the level of stress (degrees) determined? I don’t really understand what “degree of stress” I’m looking at in my personal tests, because I dont have anything to compare the stress levels to. Is there a chart or something one can use? I just figured the more severe or pronounced the corner halos were, the more stree I had, but that’s not a very difinitive answer. I guess knowing what the degrees of “accepted diviation”, for instance, as well as All degrees of stress looks like, would help me understand compatability a bit more too, since I dont have anything to measure against.

    Another dumb question, all the colors you tested above have 3 patches. Each set has a base very similar in shape to all the other colors tested, how’d ya do that? (for instance, the #3 test on all colors looks like a half dogbone! Camera trick? Just wondering ;) )

    Anyway, thanks so much Lani!
    Renee

  8. Lani says:

    Renee, Where I come from, a couple is two, but since your questions are good ones, I won’t quibble about there being five of them. One at a time…

    Q. I was under the impression that Uroboros and Bullseye were working together, they are not?

    A. No, we have not worked with Uroboros on compatibility between their glass and ours. And we have never claimed to match any standard except our own which we set over 25 years ago.

    Q. If one company (Uro) says they are making glass compatable to a company who sets a standard (Bullseye for instance), doesn’t the “standard setting” company get to police the other company so they COULD make that claim? Yes/No?

    A. You’d think so.

    Q. In your above tests, you mention “degrees of stress”, how IS the level of stress (degrees) determined?

    A. You probably slept through that part of the class: I explained it in my blog on March 28. I’m not surprised that it wasn’t memorable.

    Q. I don’t really understand what “degree of stress” I’m looking at in my personal tests, because I dont have anything to compare the stress levels to. Is there a chart or something one can use?

    A. There is no chart and there really is no need for you as a studio user to be measuring the stress to the exact degree that we do at the factory. Take a look at the examples shown above. Ideally, you don’t want to be seeing any halo at the interface between the chip and the base glass. But if the halo appears less bright than the one we’ve shown as a “4 High” (on the third chip of the Tangerine Transparent sample), you can be pretty confident of not having compatibility problems with your work. You may be able to get away with more stress in the work, but that is dependent on the size, shape, and usage of the fused piece. We try to be lots more precise at the factory than you should have to be in your own studio. We want to be certain that if you’re using our glass, you can make large, complex kilnformed works without encountering problems related to compatibility

    Q. …all the colors you tested above have 3 patches. Each set has a base very similar in shape to all the other colors tested, how’d ya do that? (for instance, the #3 test on all colors looks like a half dogbone! Camera trick?

    A. No, it’s not Photoshop. All the #1 tests were fired a single time to 1500 and held for 10 minutes. All the #2 tests were then fired AGAIN to the same temperature for the same time. That means twice the heatwork. All the #3 tests were fired a third time, for three times the heatwork of the first firing. The base clear glass is only a single layer thick. After that much heat, it (predictably) starts to pull in – or “dogbone” as it’s sometimes called. The different shapes of the base clear reflect the increasing amount of firing time they have undergone. No tricks. Just the predictable and similar changes that happen to single layers of glass after repeated firings.

    Renee, we think that users should be able to confidently use glasses that have been tested and rated as compatible from a factory without themselves having to bother with quarter wave plates and understanding degrees of angles of retardation etc. etc. Our concern is simply that manufacturers DEFINE what their testing involves and not make claims to fit the glass of OTHER factories if their testing standards are not equivalent. – Lani

  9. Lani:

    Is “Bullseye”, when used with regard to fusible glass, a trademark of Bullseye, the corporation? Just for chuckles I did a Google (Watch out Martha, he’s over there in the corner by himself doing a GOOGLE!!!) on “Bullseye” and constrained myself to “uroboros.com”. A handful of hits, none which have a “Bullseye is a trademark of…” boiler plate. If someone is using “Bullseye” in a comparative sense I’d think it would need something…

    Gary

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