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Tips, Techniques, and Questions -- Technical questions or tips

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  #1  
Old 2016-09-10, 6:10pm
Michele-MD Michele-MD is offline
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Default Black discoloration on glass rods

I tried to do pull some white and other color Bullseye glass strips today. I pre-fuse bars with murrini slices on them and then pull them to make shapes. I used an Extreme Oxygen 20 Generator and propane mix with a Minor and also a Mega Minor torch. The glass kept getting discolored and I could not burn it off. I have used a similar Extreme Oxy Gen, a 15 model, many times in my own studio and never had this problem except sometimes a small amount of discoloration on white glass. I kept turning the oxygen flow up but it did not make any difference. Any advice on why this would happen and how to fix it would be appreciated!
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Old 2016-09-10, 6:48pm
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Michele, I don't use Bullseye as a general rule, but the only time I've gotten black, smudgy soot in my glass was when my oxy was too low/propane too high. Have you changed anything else recently? Propane source? Lines flushed after each use? (Burn off all propane in line after shutting down.) Checking output of oxy generator.
Do you have any Effetre glass in the house? If you do, try a piece Rubino oro in the flame. It reduces if you look at it wrong and would give some indication of your oxy/propane mix.
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  #3  
Old 2016-09-11, 4:52am
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Try turning your oxygen down about 5% from the maximum output.

Oxycons purity can suffer if you push them right to the top.

They can go from 97% purity at 3/4 maximum to 89% purity at full out.

They need to be used just a couple of points below full blast to get the best purity out of them.
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Old 2016-09-11, 2:50pm
Michele-MD Michele-MD is offline
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Default Discoloration on Glass

Thanks for both replies.

Yes, this is a different propane tank and source. And, it has been sitting around outside for quite a while, at least 6-9 months.

I will try turning the oxygen generator down. I was definitely pushing it because it was leaking a bit around the connector and I was trying to get as much oxygen to the torch as possible.
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Old 2016-09-11, 3:45pm
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MagpieGlass MagpieGlass is offline
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I use alot of Bullseye ... it prefers an oxy rich flame.

So the above comments are spot on.
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Old 2016-09-11, 5:45pm
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I think there are filters for propane as well.

Maybe at the RV maintenance websites.
They use them to keep gunk from the bottom of the tanks from messing up the propane powered refrigerators, air conditioners and generators.

If your tank was stored on its side or if it got a lot of sloshing around during hookup you can stir up gunk form the bottom of the tank.


I feel like I need to mention hose age and hose type here as well.
Garage welding kits for acetylene have hoses that will gum up and disintegrate from the inside out if you use them with propane.

Propane requires hoses marked "Type T".


Oh and they should be replaced every ten years I think.
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