[foolmeonce]

Thanks, that article and it citations look very promising. I'm a little discouraged to see a first data point where clear is correlating with strength though since mixed color recycling waste was my first thought on sourcing. Still it gives me some ideas of areas to learn about with some specific goals in mind.

[aurizon]

Well, clarity = lack of scattering centers, which are also points of stress concentration = dislocations start here and propagate. Now glass with color from metal ions, like gold = ruby red, does not produce weakness. This mean colored glass from dissolved ions is OK, colored with particulates(pigmented) carry weakness. There is a whole gamut of the ways pigments induce weakness.