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  #26  
Old 11-03-2017, 01:13 AM
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Originally Posted by Marc Carmen View Post
Josh, I'm dying to try the durissimo. If it's a similar formula to Nero duro then it's a lead free iron sulfide black. Iron sulfide glass is not only naturally stiff but also incredibly brittle. Old glass container literature mentions that it is a cheap and easy way to black glass, if only it didn't make such an impractically brittle bottle.

Man, I have sooo many bubbly black filigrana in my student work haha.
It's not just stiff, it's CRAZY stiff! Definitely the stiffest glass I've ever played with and makes the white duro feel like enamel. I gather on the new black the instant it stops moving, which is literally walking from the gh to the furnace. If you lose the core heat you're toast. If you don't transfer it directly to a stick you're toast. Gathers needs to be done before the previous one fully sets up. Pulls need to be really hot with a faster walk than usual. If you don't have the black poking out of the end of the setup and quench before you stick to the post, you're toast. It's actually super fun to work with because it's so quirky. I've not had great luck keeping it jet black--I think it might have something to do with our gh running a bit rich (maybe Pete can explain what's up w/this). It's been going graphite grey on me--I'm going a few things to try to avoid this. I've been pulling it into cane, then bundling the cane and making murrine. I haven't used the murrine yet, but it looks excellent.

If you're into twisty cane, definitely try some of this stuff, it's wild and so much fun.
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  #27  
Old 11-03-2017, 09:10 AM
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I have not melted sulfide blacks so I'm not able to comment. Lino ran rosin blacks that were remarkable in themselves. Mine are simply chock full of oxides blotting out any color transmission. I would think Alumina is playing a major role.
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  #28  
Old 11-03-2017, 10:29 AM
Scott Benefield Scott Benefield is offline
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I'd be interested in hearing how it looks when you push the Gaffer durissimo that far, David. Stiff is one thing (as Pete says, alumina will get you that) but if it doesn't stay jet black at a hair's thickness....then what's the point?

Lino's rosin black was all that, but the melts he was doing at the old Manifesto facility were kind of unpredictable. Very fine bubbles would only appear in the final application, but not in the initial cane pull--occasionally. It was impossible to know if you had a good melt until you had taken it that far, but by then you were stuck with whatever you had. Lots of it went into the landfill.
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  #29  
Old 11-03-2017, 10:46 AM
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In the black that I periodically melt, I do pull the cane out into extremely fine thread and then taking two fingernails and run down the thread. If there's anything in it, including bubbles, you will feel them.
My larger question is really whether the gas is coming back out of solution or whether it's just in the finished rod as trapped gas. There's a difference. Color rod can be overworked.

Making color is actually really hard when you consider the standard you have to achieve . In the final analysis, it should be dense black as Scott says, or what's the point?
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  #30  
Old 11-03-2017, 10:46 AM
Kenny Pieper Kenny Pieper is offline
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Quote:
Originally Posted by Scott Benefield View Post

Lino's rosin black was all that, but the melts he was doing at the old Manifesto facility were kind of unpredictable. Very fine bubbles would only appear in the final application, but not in the initial cane pull--occasionally. It was impossible to know if you had a good melt until you had taken it that far, but by then you were stuck with whatever you had. Lots of it went into the landfill.
I have melted that black a couple of times with no problems. Its crazy how it catches on fire when it gets charged. I stays black that's for sure!
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  #31  
Old 11-03-2017, 11:57 AM
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I have melted that black a couple of times with no problems. Its crazy how it catches on fire when it gets charged. I stays black that's for sure!
Did you ever go back ??
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  #32  
Old 11-03-2017, 12:55 PM
Kenny Pieper Kenny Pieper is offline
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Did you ever go back ??
Back where?
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  #33  
Old 11-03-2017, 03:50 PM
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Back where?
Itís a joke
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  #34  
Old 11-03-2017, 04:27 PM
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Itís a joke
A rather off-color joke, Eben...

(O)
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  #35  
Old 11-03-2017, 05:40 PM
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black humor
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  #36  
Old 11-04-2017, 10:10 AM
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ďOnce you melt black, you can never go backĒ. - ancient color maker saying.
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  #37  
Old 11-04-2017, 12:06 PM
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"Melting red? Better off dead." - more ancient color maker saying.
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  #38  
Old 11-04-2017, 01:29 PM
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"Melting red? Better off dead." - more ancient color maker saying.
Truth! Hahaha
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  #39  
Old 11-04-2017, 07:54 PM
Marc Carmen Marc Carmen is offline
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Originally Posted by David Patchen View Post
It's not just stiff, it's CRAZY stiff! Definitely the stiffest glass I've ever played with and makes the white duro feel like enamel. I gather on the new black the instant it stops moving, which is literally walking from the gh to the furnace. If you lose the core heat you're toast. If you don't transfer it directly to a stick you're toast. Gathers needs to be done before the previous one fully sets up. Pulls need to be really hot with a faster walk than usual. If you don't have the black poking out of the end of the setup and quench before you stick to the post, you're toast. It's actually super fun to work with because it's so quirky. I've not had great luck keeping it jet black--I think it might have something to do with our gh running a bit rich (maybe Pete can explain what's up w/this). It's been going graphite grey on me--I'm going a few things to try to avoid this. I've been pulling it into cane, then bundling the cane and making murrine. I haven't used the murrine yet, but it looks excellent.

If you're into twisty cane, definitely try some of this stuff, it's wild and so much fun.
Thank you David! Copied and pasted into my notes. I'm sure you saved me some headaches
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  #40  
Old 11-05-2017, 08:55 AM
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Mark talked about cad/sel reds in fluorine that started off compatible in his work and by the time he was done, they were no longer compatible. The effects of heating and cooling repeatedly in a glass does often change them. While John is really cautious about using Hagy seals to determine mismatch, those efforts can sometimes be defeated. The description of the black makes me think of those circumstances.
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  #41  
Old 11-05-2017, 01:37 PM
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Originally Posted by Pete VanderLaan View Post
Mark talked about cad/sel reds in fluorine that started off compatible in his work and by the time he was done, they were no longer compatible. The effects of heating and cooling repeatedly in a glass does often change them. While John is really cautious about using Hagy seals to determine mismatch, those efforts can sometimes be defeated. The description of the black makes me think of those circumstances.
I've worried about this as well. Theres definitely some crystal growth going on. Some of the FeS test melts I've done needed to be struck from a dark trans brown to that characteristic gritty graphite black, but only if the melt wasn't reduced enough.

I've never had compatibility problems though. Then again, the density of the color never requires more than a thin overlay or a fine cane.
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  #42  
Old 11-06-2017, 04:14 AM
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Quote:
Originally Posted by Pete VanderLaan View Post
Mark talked about cad/sel reds in fluorine that started off compatible in his work and by the time he was done, they were no longer compatible. The effects of heating and cooling repeatedly in a glass does often change them. While John is really cautious about using Hagy seals to determine mismatch, those efforts can sometimes be defeated. The description of the black makes me think of those circumstances.
This is why I never use cad/sel colors in murrine. Too many heat cycles blows the fit. I got this tip from John C a decade ago.
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  #43  
Old 11-11-2017, 11:15 PM
Marc Carmen Marc Carmen is offline
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Pete, have you ever considered taking your black formula and adding alumina to stiffen it up? I mean like really stiff, like the way David is talking about working with the durissimo. I'm wondering if all that added alumina would offset the benefits of the lead base in terms of solubility of metal oxides.

I get what you and Scott are saying with the staying jet black. I think its also just as important that it stays crazy stiff. Maybe one day we could get the best of both worlds. Gaffer seemed to go the FeS route and some people complain about the color. I for one embrace the gritty warm black of it.
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  #44  
Old 11-12-2017, 09:29 AM
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Well, the leaded black is a lot more expensive to make. I'm adding lead now to keep it from devitrifying already.alumina would push back hard.
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