Testing Protocol For Stained Glass
Posted: Sat Oct 27, 2012 11:30 am
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!
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!