It all seemed so simple: I wanted brightly colored powders, like the TE9000 series developed for Moretti (now Effetre/Vetrofond) for Bullseye. Easier said than done, at least given the state of my ignorance. After getting ready to email an updated version of my researches for the third time, I finally wised up, and decided to start a journal-entry style webpage.

Here is a (very) rough timeline of my researches:

1999?—I decide I love TE9000 for Effetre. I make a sample set of all the colors, rolling a ~12mm hollow bead of 004 clear in each, and stringing it with a tag.

2001?—I hear on the grapevine Pam Dugger uses some special TE on her frit and powder beads. She certainly manufactures in colors not available in the Effetre palette.

2002?—Arrow Springs starts carrying the TE7000/8000 series, which they say are for “spectrum and bullseye” (i.e. 96 and 90 glasses.) I bought the lot.

Took ’em home, waxed lids on watchmaker's tins, labeled and dished ’em out. Made samples of each on schott clear ~12mm schott clear beads, of which 1/3 or so cracked. Whoopsie!

Flummoxed by this obvious failure I put the enamels away, resolving to deal with them at some future date.

2003? read in Lundstrom's fusing book that various types of Thompson enamels could be mixed to adjust them to the compatibility of the base glass. This struck me as interesting project, preferably after I hooked up with someone who had a) more fusing experience than I do and b) a larger and more efficient kiln. Though my AS AF99 is advertised as a fusing kiln, and it will indeed reach fusing temperatures, it leaks heat and is inefficient at these temperatures.

August? 2004 Encountered a TE rep, who encouraged me to contact the company about my problems. He was strangely defensive.

October 2004 took a class from Stevi Belle, and made the interesting discovery that her frit and powder beads incorporate German powders and frits, such as Friedrich (Kugler), Reichenbach (Q-colors) and Zimmerman brands, which have been developed for the glassblowing market, and whose lead-bearing qualities functionally give them a greater working range of coe's. Though listed in the high 80s, for working purposes can be considered to be 91–94.

During Stevi's class I made some test beads, either on schott or bullseye clear, of some of her frits and powders None of the beads broke within one day. However, German frits and powders are sold in 1/2 KG lots; and before investing in what would be a lifetime supply of them, let alone palming them off on various friends, I thought it might be prudent to do some research. Perhaps it might be worthwhile resurrecting the TE?

13oct04: Contacted Thompson Enamel, and spoke to a chemist.

In a nutshell, the chemist in charge of developing this product left the company before finishing it, and it was really formulated for 96 spectrum, not 90 bullseye. They only sell about 20# of it a year, so they've got no plans to develop it. No wonder the sales rep was squirming when I talked to him last summer!

With the bullseye, the guy said, you'll have about a 50% failure rate,^[1] which in fact is what my samples show. In fact, we have good, but not, you'll note, perfect agreement:

The one day and 12 month (actually I think it was 1 month) failures were provided by the Bullseye technical guy, off a list from 2002. He recommends 6-12 months of holding on to pieces before sale to test for these sorts of problems.

He also said there was no published data as far as he knows for combining this line of thompson enamels with another to make it truly compatible for Bullseye. The way to do it, he says, is to mix the 5000/6000 stuff formulated for float glass. He suggests starting with opaques, with roughly a 4:1 ratio (4 parts 7000/1 part 5000). Well, actually there aren't that many transparents, except sort of a cranberry that I care about, and those are always a pain (but so pretty) —I know Stevi mentioned some of the German transparent cranberries (gold pinks) could be problematic.

In order to avoid visual speckling (which might actually be an attractive effect) you can't just put the powders in a jar and shake them, because they're different weights. You have to put them on a newspaper and fold one side to the other; reverse, then do top to bottom and bottom to top to mix. Tedious. He says people mixing flour and what not mix dry ingredients this way, which I'd never heard of, just folding in of eggwhites (the powder mixing method is also called folding.)

At least the 5000/6000 colors could be used float glass if they didn't work out for mixing! They've been working hard to get those whipped into shape, and I guess they're pretty successful (90%+) so long as you use american-manufactured float glass.

Though I think the TE company is foolish in the extreme to market a product so “buggy” (as a computer hacker would put it), the company is to be congratulated for putting customers in contact with knowledgable employees, and this guy gets top marks for technical expertise and candor. I was very impressed with him. Now that Bullseye has come out with so many new colors for lampworkers, it might be worth their while to finish this product line—I felt a polite letter to this effect might be useful, and the chemist to whom I spoke agreed that a sentiment coming from a customer would have greater impact. It's on my to-do list.

So then I contacted Kate Fowle Meleney, who was instrumental in developing the 9000 series. She has “used them [TE7000/8000] sparingly on Bullseye with no ill effects, but have never completely covered a Bullseye surface with enamel. I'd say 90% of my work is with Effetre.”

Her suggestion was to use Kugler instead, since that's what she thought “ Stevi Belle and Karen Ovington use.” And, of course, she's absolutely right. She also told me her method for testing:

“By the way, before Thompson and I worked on the 9000 series, I probably made about 2000 test beads using the other enamels they made on Effetre. I would make a core of Effetre, heavily roll it in enamel, then encase it with more Effetre. If that lived to see the light of day, I would also make an Effetre bead and roll it heavily in Thompson and melt it in and leave it on the surface. After it was annealed, and up to even a week or more later, I would watch for a network of little cracks appear in the enamel. Those ended it to the trash. If the enamel didn't form cracks, I deemed it more or less compatible.” However, she never conducted tests for Bullseye.

Therefore, the obvious thing to do is a fusing test (as detailed in the Lindstrom book), at least of the colors that don't crack, to see if some might be salvageable.

Long Term Plans

20oct04 Canterbury glass is having a sale on Bullseye sample frit and powder packs. Hmm, good for a baseline, if nothing else. For the time being, however, I will probably focus my energies on testing the German powders on Bullseye.

I've also spent several hours trying to match my scribbled notes to my samples from Stevi's class to the stock numbers listed on Olympic Color Rod, the Friedrich site, etc. So far, none of the samples have cracked, and I have three good reasons to believe these are less problematic than the TEs:

1. Stevi Belle and Karen Ovington have used German powders successfully for years;
2. the nominal coe (91–94) is closer than the target (96) of the TE7000/8000
3. German powders are lead bearing, with lower viscosities, which means they're more tolerant of coe differences.

I think I'm finally starting to understand why coe variations can be greater with low-viscosity glasses (remember, viscosity is the inverse of fluidity—very helpful way to think of it, thank you Mr. Grimmett.) Publishing a list of my samples from Stevi's class is now also on my to-do list. (Correlating other lampworkers’ favorites with stock numbers is also on the to-do list: and the stock number for silver blue, for three points and a dog bead is...?) I've located a fuser with a big kiln who has some interest in doing a bunch of tests—but no sooner than 2005, please. As I am up to my eyeballs in other projects, that's fine with me. Still, the would-be glass chemist in me beckons...

Unless otherwise noted, text, image and objects depicted therein copyright 1996--present sylvus tarn.

Sylvus Tarn