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Everything posted by ann
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Well. The first thing that comes to my mind, which can probably be answered by someone here who's seen it done, is how are these achieved? I don't know, but from the ones I've seen I would guess, from the appearance of the surface, that it has something to do with the surface of the gob of glass being very slightly too cool before it hits the rollers? They seem to consistantly have fine cold rolls that follow / form the pattern . . . Or maybe the surface temperature when the stream hits the shears? Or both? I don't know. And the few Pelts I have with that pattern don't consistantly have the same fine cold rolls, although some certainly do. Wait. I could be lying. I have to check the Pelts tonight. In the meantime, all others chime in. And that should be DAS, not Das. But I don't know how to change it up there.
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I'm going off with Ron to get popcorn. We'll be right back. Steph? Wanna start a DAS Ram's Head thread? That's the one that particularly interests me, reminding me as it does of some of the early Pelts (usually called yin-yang or zig-zag ones. And may or may not include individual "Miller Swirl" examples?) Sorry John -- but I hoped maybe "fluid dynamics" would get your attention!
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Hello John! And OMG you're right -- Fig. 7 does look more like a wirepull, even though that's not really what's described . . . Your chevron reference explains to me (for the first time) the weird wood-grain-knothole-like pattern on a lot of Pelt slags. And I think you made an interesting point that brings in some of what Ron was saying too - - - One final point, the key is that the glass stream hits the side of the second conical nozzle. This constrains the glass and the direction of "wobble" or "waver". If the stream where to hit at the center, it could move freely 360-degrees and wrap like a "flame" or become a "wire pull." Wish I had something to sell . . .
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Nice! Happy Birthday!
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Definition Of A Machine-Made Swirl
ann replied to westcoast_dave's topic in General Marble & Glass Chat
Striations, clear, transparent, in suspension in the clear mass being the operative words . . . I agree that with tweaking that set-up may have been used for other effects as well. But as Ron has pointed out, it's not really necessary to use that set-up if you want ribbons on an opaque body glass. The distance from the orifice to the shears and how the stream hits the shears (and other factors) can produce what would wind up looking like an NLR. -
Sure, wait till I'm out of town for Turkey and bring this up again. OK. Yes, patent 1,927,650 would produce the feathered slags. I have no arguments different from the ones I've used before (Mibstified homework thread link!) If you know that patents are legal documents written by lawyers you understand how very important precise terminology is . . . like the use of the word "striated" in this patent. Not striping glass. Not ribbons of glass. Striating glass. In a transparent base. There's even a drawing of the kind of marble that would be produced in the upper left corner of Figure 1 (it's figure 7). It's no NLR. Most basically, there is no need for anything like the device in the patent, which is primarily concerned with internal striations, if you're going to use an opaque body glass. You can get ribbons (or flames, or whatever) on opaque body glass without the patented mechanism above the orifice. The shamrock marble guy, who is also a fluid dynamics guy, agrees with me. Or at least a very irritated marble friend of mine tells me that he does.. But I still love migbar anyway. He's just misguided. I am sure in time he can be put right.
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Definition Of A Machine-Made Swirl
ann replied to westcoast_dave's topic in General Marble & Glass Chat
No, not from separate furnaces. The white glass stream was introduced frorm the side of the furnace containing the transparent colored glass, near the orifice. Hmmm. Have to go check about whether the white was introduced there as cullet or as already-molten glass. I forget. Been awhile since I looked at that stuff. But I suppose, for our purposes, it doesn't really matter, since the transparent color and the white together were funnelled into the single orifice from the one furnace. So . . . either pot or single stream for slags, is what you're thinking? To be continued . . . -
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Not sure what you think "black" is, but as a color (as opposed to light) it is a mixture of all colors. Basic color science. But then I'm also of the "if it walks like a duck and looks like a duck and quacks like a duck" then it's a duck, school. At least here. I can't help but think that if glass is so dark and dense that it appears to be black -- completely opaque, no light whatsoever can penetrate it -- what else is it but black? Actually, all the old guys needed to obtain opaque black was arsenic, plus a whole bunch of manganese oxide, and a few other things (cobalt, coal, and some people used . . . well, not to put too fine a point on it . . . sheep dung. Don't know whether other dung varieties were used or not. So I dunno. I understand your point, but I don't really understand your definition of black. In the meantime, I'm going with the professional glass chemist, Henry Hellmers. And his predecessors. P.S. I don't think of you as the new guy. Maybe because I'm gettin' real old myself, but it seems to me you've been here long enough to not fall into that category any more. FWIW!
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I agree. Pelt.
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Love it! Looks like what Paul Baumann called "streamer" marbles.
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Definition Of A Machine-Made Swirl
ann replied to westcoast_dave's topic in General Marble & Glass Chat
Well. I hadn't thought of the slag / transparent swirl in those terms before. Going to go off in a corner and mull it over. It just might work . . . Or not. Just occurred to me that from what I've seen, the transparent color and opaque white of the Pelt feathered slags were put together in the furnace, not a pot . . . hmmmmm . . . -
Re the Venetian bead world, think different countries, different purposes. Glassmakers have always been secretive about their formulas, and none so more than the Venetians. Also, the beads you're talking about, "French Ambassador," "Lewis & Clark," etc. were mostly black-glass-based, best as I remember. Whoops, that pesky black glass again. And marble glass was somewhat different than bead glass, in that it quite literally was going to take hard, percussive hits from other glass and stone projectiles . . . bead glass didn't need to be quite so rugged. Which would have changed the basic formula somewhat. The Greiners used some opaque glass colors that I'm sure they developed themselves. But I don't think their formulas for opaque colors were known outside their small circle.
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Definition Of A Machine-Made Swirl
ann replied to westcoast_dave's topic in General Marble & Glass Chat
The distance of the drop between the orifice and the shears also matters . . . -
What patents are you talking about? The old glass formulas weren't patented. I seem to have missed something . . . It doesn't matter to me whether or not you believe there is or is not black glass. Not trying to convince you. Just giving you information. You can certainly have your opinion about it -- as can we all --, but you really shouldn't say that it "is just not the fact of the matter" when what you're saying is opinion -- not fact. You've certainly surprised me.
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Yep. A few of my old German swirls have black -- and it's very black. No hint of color under strong light.
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Your intuition is right. When you're talking about pigments (sez the cranky old art historian), black is the presence of all colors. (When you're talking about light, however, the presence of all colors gives you white. How annoying.) Anyhoo, there's a little more variation in the formulas for black than I expected to see, although I can make some generalizations. In addition to sand and soda, the most common ingredient used as a colorant is manganese oxide, which shouldn't surprise anybody. Although there are a few formulas without it. Those mostly have coal and some sulfur. Here are two formulas from Akro Agate, both noted as "Black opal dense good" in 1928. The ingrediants vary slightly; the first number is from one formula, the second number is from the other one. Measurements are in pounds. >> insert "first you get a bunch of sand" jokes here << Sand 1000 1000 Soda 360 360 Nitrate 40 37 1/2 MnO2 25 25 (This is the magnese oxide) Cobalt 1 1/4 1 7/8 Feldspar 250 300 Fluorspar 110 102 Sod.sil.fl 40 50 Pot. Bichrom. 5 6 1/4 Nickle ox. 2 1/2 2 1/2 For comparison, here's the one for Lawrence Glass (1932) Sand 600 Soda 300 Limestone 60 Coal 30 MnO2 80 Cobalt 1/2 Pot. Bichrom. 7 Nickle ox. 5 Some variations arn't in colorants so much as to adjust the glass to be heat-resistant or to be used in pressed-glass ware . . .
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What he ^^^ said.
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It looks like it was happening at some places. I have a copy of Henry Hellmers' (Akro's glass chemist) batch book, and in it he has several pages of formulas for "Black or Ebony Glass," with the oldest dated 1927. Several formulas each for (among others) Cambridge Glass (1930, 1931, 1932), Akro Agate (1928), and Lawrence Glass, Sistersville (1932). I think most companies used whatever could give them the appearance of black, whether it was dark purple, dark blue, dark green, etc., and from that came the generalization that "there is no black glass." But there is. And was. You just don't see it often. Think back to the so-called "Indian." They're black, except for the occasional "maglight Indian" using deep purple, blue, green -- I even have an amber one. And the black used in a late minority of the old German swirls. A couple of Hellmers' formulas are old German ones . . . If I get realy bored later, I'll sift through them for the common ingredients , , ,