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

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  #1  
Old 2017-06-29, 12:52am
pswrd pswrd is offline
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Default Resources for learning more about colour chemistry and COE

Is there anything out there that has in depth information about the chemistry of coloured/colouring glass? Just hoping to understand that more to get a better appreciation of the properties and behaviour.
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  #2  
Old 2017-06-29, 6:40pm
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I remember Bulseye having a web page with things like sulfur, copper and various other colorants with indications on how they interact.
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  #3  
Old 2017-06-29, 6:50pm
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Here are some of my saved favorites that might guide you towards what you are looking for.

The first one by Kay Powel is terrific and well worth reading in its entirety;
http://www.listen-up.org/kitty/index.html

This one in particular;
http://www.listen-up.org/kitty/beads...or%20chart.htm

And then these other two;
https://web.archive.org/web/20060404...olorchart.html

And;
http://www.wetcanvas.com/forums/showthread.php?t=464446
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  #4  
Old 2017-06-29, 6:55pm
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Please come back to this posting and tell us what you learn to make it easier for us to find in the future.
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  #5  
Old 2017-06-30, 1:13am
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Aye, the designation of 104 or 96 coe is a coefficient of expansion but those values are all very relative and are calculated through the chemistry tables while the glass is at certain temperatures in a laboratory setting with very specific mixes of the chemicals that make up the glass.

Unfortunately the way to manufacture glass for our use shows that the numbers don't scale up for production runs in quantities of tons or even hundreds of pounds of glass.

And those coe values are only for a specific range of temperatures.

Another thing to remember is that the yellow flare is sodium burning off from the molten mix of chemicals so the chemistry is actually changing as you watch it in the flame.

Work it in the flame too long and it will stiffen up alot and even change color.

When you get around to studying how to make glass in quantity you find out that the colorants are on the order of one pound of colorant to 300 pounds of base glass chemicals and even an ounce of contaminants in the 300 hundred pounds of base glass batch can not only change the end color but also change the way it melts and / or cools and how well it tolerates being melted to the surface of another color with its own characteristics of heating and cooling properties.

So when someone says "this is coe 104 glass" it could be anything from 101 to 108 when actually tested and still be considered coe 104.

The difference between Devardi glass made in India and Effetre made in Italy is a classic example.
Most Effetre melts like butter while a lot of Devardi will hold its shape like clay pretty much no matter how hot it gets.

But they are both considered coe 104 glass.
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Old 2017-06-30, 1:18am
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I signed up for a years access to the Bulseye website for $40 and they have really great videos on glass characteristics.

If you have the funds it is a great return on the value.

Even alot of their free videos are worth your time.
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  #7  
Old 2017-07-01, 6:13am
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I would not think it mad at all to use Bulseye sheet goods for lampworking.

I am under the impression that a lot of stained glass artists started lampworking with scraps from the stained glass cut offs.

I may well have done so if I had not already invested a lot of cash in soft glass.

My ability to get stuff mixed up and confused has me restraining myself from exploring any other coe glass no matter how enticing the colors.
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  #8  
Old 2017-07-03, 7:25pm
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Also the books by Bandhu Scott Dunham are a wonderful resource on the chemistry of glass.
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