Recycled glass and compatibility

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I recently participated in a group show, kiln processes using recycled
glass, sponsored by the Center for Environmental Economic Development
(CEED) in California.  www.ceedweb.org/glass  The show was terrific,
the stuff by other artists, some functional, some decorative, was
really interesting.  The folks who run CEED, Ruthanne Cecil, Program
Director, snipped-for-privacy@humboldt1.com>, Robert Kirby, Recycled Glass Engineer,
snipped-for-privacy@earthlink.net>, and Ed Boisson, Project Manager,
snipped-for-privacy@att.net> are knowledgeable and very helpful.  Some of the most
interesting products were tiles and tables made from recycled bottle
and tempered glass.

I work mostly with bottle glass.  The thermal coefficients of this vary
widely.  So compatibility is always an issue for me.  I don't routinely
test for compatibility - it would take lots of time.  So I just work
from experience and allow extra time for annealing.  One thing I
learned from the CEED folks is that glasses that are not compatible can
be fused successfully if they are broken into small pieces and well
mixed.  It doesn't matter what the thermal coefficients are.  Tiles and
tables can be made from all sorts of bottle or other glass, without
regard to compatibility.  I'm using smaller pieces in my own fusing,
and it seems to work.

John Bassett


Re: Recycled glass and compatibility
Hi John,
That's some interesting info.
Have you tested these fused pieces by putting them in the freezer?

--
Connie Ryman
Cryman Studio

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Re: Recycled glass and compatibility
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learned from the CEED folks is that glasses that are not compatible can
be fused successfully if they are broken into small pieces and well
mixed.  It doesn't matter what the thermal coefficients are.  Tiles and
tables can be made from all sorts of bottle or other glass, without
regard to compatibility.  I'm using smaller pieces in my own fusing,
and it seems to work. <
 Small pieces have more surface area per unit volume thus less material
pulling on more area, so compatibility should be less of a problem.
 "doesn't matter"  within the limits of bottle glass which doesn't have a
huge range anyway.
 annealling longer should not make a difference, the difference in COE, if
it is enough, will still set up a strain while cooling that may be enough to
break off bits or break the pieces.   Annealing is supposed to relieve the
strain of working and initial solidification.   I have some paperweights
with small pieces of incompatible color inside that show lovely silver shear
planes inside the glass.

--
Mike Firth
   Furnace Glassblowing Website
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Re: Recycled glass and compatibility

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   I rarely have success mixing different colored glasses together.


--

JK Sinrod
www.sinrodstudios.com
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Re: Recycled glass and compatibility
Thanks for the comments.
I've only freezer tested large pieces of green bottle glass fused to
some clear bottle glass.  This usually works.  Yellow bottle glass only
seems to fuse with brown.  Yellow and anything else doesn't seem to
work.  The folks mixing really small pieces of bottle glass and making
tiles or tables have exposed these tiles and tables to weather over
time.  I assuming that fusing is OK.  I haven't done this myself.  I
understand that what you say is right that extra annealing time is not
helpful.  I'm cautious because what I fuse may vary from 1/16' to 3/4"
thick.  I have had failures of pieces containing only one kind of
glass.  I assume these were due to under annealing.  My sense is that
Bob Kirby and other folks at CEED know much more than I about working
with recycled glass.

John Bassett
Glassman wrote:
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Re: Recycled glass and compatibility
  See, you are using related colors which is the most common factor in
mismatched COE.
  In Kugler color, which is widely used in glass blowing, the yellow is
notorious for causing
COE failures in glass that supposedly matches.

--
Mike Firth
   Furnace Glassblowing Website
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