It’s only two weeks since Halloween; I should have expected to find this bogeyman still lurking around.
Boo! Guess what? This is NOT compatible by Bullseye’s standards. This is Uroboros red frit fired three times on Bullseye T-glass. The shocking white halo is stress. Lots of it.
Yesterday this post jumped out at me from a thread on the Warm Glass Bulletin Board:
“…I’m sure the folks at Bullseye would not agree but I know that many glass studios use [Bullseye and Uroboros] together with no problem.” (post #15 in the thread)
Wrong. We folks at Bullseye would agree that many fusers get away with fusing Uroboros and Bullseye together. I expect that there are thousands of earrings and cabochons and plates and Xmas ornaments happily floating around the fuseosphere that include pairings of glasses made by our two factories.
But experienced fusers will tell you that there is no such thing as “universal compatibility”. Just because it works in small work, or thin work, or blown work, or work that’s been fused only once, does not mean that it will work in larger, thicker works subjected to multiple firings or environmental challenges.
At Bullseye we put our most challenging glasses through triple-fire tests. Unless, after all three firings, they remain within the range of our published standards, we do not label and sell them as “compatible”.
Furthermore, we would not dream of claiming this level of compatibility with glasses made by another company without knowing their testing protocol and standards and without both our factories using the same test glass standard.
Users have consistently reported problems when fusing Uroboros reds, yellows and oranges with our glass. We have researched the problem and could not disagree with their reports. Last year I blogged on this issue – and the larger problem of glass companies not publishing their specific testing protocol and compatibility standards.
Folks, fuse together whatever glasses you want. But please do not advise beginners that there are “no problems” with the fit between Bullseye and Uroboros. We only wish that were true. It is not.
This is the Uroboros “marigold yellow” that users (on the WG Bulletin Board) have often reported having problems with when fusing to Bullseye:
Am I beating a dead horse here? Are these random odd batches? Hardly.
I blogged on this same subject and these same glasses over 18 months ago. (Commingled with some disjointed musings on my dead cat, Ed)
The samples I posted in May of 2007 (scroll down the post) were of sheet glass purchased at Cline Glass here in Portland. These latest samples are frit purchased through Delphi seven months later.
Same results. I suppose they should get high marks for consistency.
PS. If you want to read the entire rant about why matching COEs does not insure compatibility, you can start here and follow the discussion for the subsequent two months. Again, you’ll need to navigate between a dead cat and Jun Kaneko to get through it all.