Like many newcomers to kiln forming I have spent a fair amount of time with stained glass, small to large projects, have tables, hand tools, grinders, saws, etc. My Father got me started and between the two of us we have accumulated a lot of stained glass stock, hundreds and hundreds of pounds in sheets all the way up to 3'x4'. Obviously I'd like to use some of this glass for fusing/slumping and have read about testing with polarized filters, looking for stress halos, etc. I have searched here and in other forums for details and still have some questions. Sorry if this has been answered before, my search-fu may have failed me.....
1) I assume I will need to test even single type firing of any given stained glass to understand how it reacts, changes color, etc. What size square is suffcient for this testing?
2) For fusing a single type/color with itself either in sheets or in strips, can I assume low odds for cracks, fractures or other problems associated with compatibility? (Since there is only one glass involved). If not, what test set up is recommended for fusing a single type with multiple pieces?
3) To test compatibility of this glass I assume I would fuse squares on clear glass that has a known COE. I would fuse on clear COE 96, ID the ones without evidence of stress, catalog them as COE 96 possibles. Then re-test the types that failed the 96 test using COE 90 clear, log those that pass that test as COE 90. I assume some would pass neither test and I'd set those aside (for now). After this testing could I reasonably expect the glass grouped by apparent COE to be compatible for fusing with each other and with new fusing glass of the same COE? If not, then how would I test 3-4 different glasses (say all non-transparent) with each other before building/fusing a large project with them?
4) What firing schedule is recommended for these tests? Full fuse to start with?
These may be the wrong questions to ask and I know this will be a long drawn out process. Just trying to figure out how to re-use a tremendous amount of glass on hand. Thanks!
Testing Protocol For Stained Glass
Moderator: Tony Smith
Re: Testing Protocol For Stained Glass
You might find this tech note from Bullseye helpful http://www.bullseyeglass.com/images/sto ... tes_03.pdf
I tried using art glass when I started but very quickly decided it was a waste of time, materials and effort. All better spent using 90 or 96 glass. Still have my stacks of art glass but am actually going to list it on Kijiji (like a Craigs list) and try to get rid of it, I need the space.
I tried using art glass when I started but very quickly decided it was a waste of time, materials and effort. All better spent using 90 or 96 glass. Still have my stacks of art glass but am actually going to list it on Kijiji (like a Craigs list) and try to get rid of it, I need the space.
Re: Testing Protocol For Stained Glass
Thanks Mary Lou, I missed this one when researching. Printed and filed.
I guess this means the answer is the infamous "It depends", and the only way to really know is test each type of glass with any others that may be included in the project? No way to do a rough sort beforehand? Wow.....
Lindy
I guess this means the answer is the infamous "It depends", and the only way to really know is test each type of glass with any others that may be included in the project? No way to do a rough sort beforehand? Wow.....
Lindy
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Stephen Richard
- Posts: 302
- Joined: Sun Jul 06, 2003 4:36 pm
- Location: Glasgow, Scotland
- Contact:
Re: Testing Protocol For Stained Glass
"Like many newcomers to kiln forming I have spent a fair amount of time with stained glass, small to large projects, have tables, hand tools, grinders, saws, etc. My Father got me started and between the two of us we have accumulated a lot of stained glass stock, hundreds and hundreds of pounds in sheets all the way up to 3'x4'. Obviously I'd like to use some of this glass for fusing/slumping and have read about testing with polarized filters, looking for stress halos, etc. I have searched here and in other forums for details and still have some questions. Sorry if this has been answered before, my search-fu may have failed me.....
1) I assume I will need to test even single type firing of any given stained glass to understand how it reacts, changes color, etc. What size square is suffcient for this testing?
2) For fusing a single type/color with itself either in sheets or in strips, can I assume low odds for cracks, fractures or other problems associated with compatibility? (Since there is only one glass involved). If not, what test set up is recommended for fusing a single type with multiple pieces?
3) To test compatibility of this glass I assume I would fuse squares on clear glass that has a known COE. I would fuse on clear COE 96, ID the ones without evidence of stress, catalog them as COE 96 possibles. Then re-test the types that failed the 96 test using COE 90 clear, log those that pass that test as COE 90. I assume some would pass neither test and I'd set those aside (for now). After this testing could I reasonably expect the glass grouped by apparent COE to be compatible for fusing with each other and with new fusing glass of the same COE? If not, then how would I test 3-4 different glasses (say all non-transparent) with each other before building/fusing a large project with them?
4) What firing schedule is recommended for these tests? Full fuse to start with?
These may be the wrong questions to ask and I know this will be a long drawn out process. Just trying to figure out how to re-use a tremendous amount of glass on hand. Thanks!
lbailey"
I used to do exactly this kind of thing before fusing glasses were easily available here. In general I found that opalescent glass did not stand up well to firing to fusing temperatures, whatever the manufacturer. So I recommend that you eliminate all the opalescent glasses from your tests. Wispy glass sometimes works ok, but devitrifies easily, so a devit spray is needed.
I do not try to cross manufacturers on the whole. Test against a clear when testing, then you have a single standard, knowing that anything compatible with the clear will be compatible with each other. Your proposal to test against Spectrum 96 or Bullseye does not seem to be one that will be productive. By all means, test Spectrum glass against S96 clear to see which are compatible. I found that the old Armstrong in some instances was compatible with spectrum )(but any hint of opalescence meant severe devitrification even to the stage of crumbling away)
You can assume compatibility for glass from the same sheet (otherwise the sheet will not cut well), so no tests other than resistance to devitrification are required.
I run a strip test for compatibility as it lets you test a lot more glass colours than the chip test does. http://glasstips.blogspot.co.uk/2009/08 ... tests.html
To repeat, it is not worth trying compatibility tests for opalescent stained glass, as it will devitrify in the most amazing ways. Compatibility is not the issue for opalescent glass, if it cannot get past its tendency to crystalise and crumble. Save yourself a lot of time and keep your opalescent glass for stained glass or mosaics, or to sell on to someone else.
Remember to include an annealing test on each compatibility test, as there is no easy way to distinguish between annealing and compatibility stresses.
Steve
1) I assume I will need to test even single type firing of any given stained glass to understand how it reacts, changes color, etc. What size square is suffcient for this testing?
2) For fusing a single type/color with itself either in sheets or in strips, can I assume low odds for cracks, fractures or other problems associated with compatibility? (Since there is only one glass involved). If not, what test set up is recommended for fusing a single type with multiple pieces?
3) To test compatibility of this glass I assume I would fuse squares on clear glass that has a known COE. I would fuse on clear COE 96, ID the ones without evidence of stress, catalog them as COE 96 possibles. Then re-test the types that failed the 96 test using COE 90 clear, log those that pass that test as COE 90. I assume some would pass neither test and I'd set those aside (for now). After this testing could I reasonably expect the glass grouped by apparent COE to be compatible for fusing with each other and with new fusing glass of the same COE? If not, then how would I test 3-4 different glasses (say all non-transparent) with each other before building/fusing a large project with them?
4) What firing schedule is recommended for these tests? Full fuse to start with?
These may be the wrong questions to ask and I know this will be a long drawn out process. Just trying to figure out how to re-use a tremendous amount of glass on hand. Thanks!
lbailey"
I used to do exactly this kind of thing before fusing glasses were easily available here. In general I found that opalescent glass did not stand up well to firing to fusing temperatures, whatever the manufacturer. So I recommend that you eliminate all the opalescent glasses from your tests. Wispy glass sometimes works ok, but devitrifies easily, so a devit spray is needed.
I do not try to cross manufacturers on the whole. Test against a clear when testing, then you have a single standard, knowing that anything compatible with the clear will be compatible with each other. Your proposal to test against Spectrum 96 or Bullseye does not seem to be one that will be productive. By all means, test Spectrum glass against S96 clear to see which are compatible. I found that the old Armstrong in some instances was compatible with spectrum )(but any hint of opalescence meant severe devitrification even to the stage of crumbling away)
You can assume compatibility for glass from the same sheet (otherwise the sheet will not cut well), so no tests other than resistance to devitrification are required.
I run a strip test for compatibility as it lets you test a lot more glass colours than the chip test does. http://glasstips.blogspot.co.uk/2009/08 ... tests.html
To repeat, it is not worth trying compatibility tests for opalescent stained glass, as it will devitrify in the most amazing ways. Compatibility is not the issue for opalescent glass, if it cannot get past its tendency to crystalise and crumble. Save yourself a lot of time and keep your opalescent glass for stained glass or mosaics, or to sell on to someone else.
Remember to include an annealing test on each compatibility test, as there is no easy way to distinguish between annealing and compatibility stresses.
Steve
Steve Richard
You can view my Blog at: http://verrier-glass.blogspot.com/
You can view my Blog at: http://verrier-glass.blogspot.com/
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Rick Wilton
- Posts: 273
- Joined: Sat Oct 25, 2003 8:18 pm
- Location: Calgary, Canada
- Contact:
Re: Testing Protocol For Stained Glass
It's not all that cut and dry. Just because Glass A is compatible with glass B and glass B is compatible with glass C doesn't necessarily mean that A and C are compatible.
COE is just one variable to making them compatible. There are others equally as important, hence the reason Bullseye doesn't call there glass "90" they call it "tested compatible" Spectrum calls their glass "96" but I highly doubt that all their glass is actually a 96 COE as the expansion has to change with viscosity, especially with extreme differences in viscosity like and black and white.
COE is just one variable to making them compatible. There are others equally as important, hence the reason Bullseye doesn't call there glass "90" they call it "tested compatible" Spectrum calls their glass "96" but I highly doubt that all their glass is actually a 96 COE as the expansion has to change with viscosity, especially with extreme differences in viscosity like and black and white.
Rick Wilton
Re: Testing Protocol For Stained Glass
A lot of that juicy stained glass may strike at kilnforming temps- ring mottles will disappear, colors will get muddy - but it doesn't hurt to put some samples in the kiln to find out.
Re: Testing Protocol For Stained Glass
Great feedback guys, thanks so much for the input. This will help me plan some realistic testing. Still in the early stages, ordering a kiln soon, preparing the work space, taking all the SG gear out of storage, etc. I will post some results but it may be a while before the initial tests are completed.
I hope you won't mind other questions as they come up, thanks again.
Lindy
I hope you won't mind other questions as they come up, thanks again.
Lindy
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S.TImmerman
- Posts: 235
- Joined: Wed Nov 25, 2009 9:23 am
- Location: San Diego ,Ca
Re: Testing Protocol For Stained Glass
I, like many did stained glass for a few years and actually bought a kiln to embellish my stained glass with painted elements- that was three kilns ago and a small fortune in tools, machines and knowledge.
This place, these people, you won't find a more helpful, knowledgeable, thoughtful , lot.
Welcome, Lindy
Shereen
This place, these people, you won't find a more helpful, knowledgeable, thoughtful , lot.
Welcome, Lindy
Shereen