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Old 07-18-2021, 03:25 PM
Jed Hannay Jed Hannay is offline
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Originally Posted by Paul Stout View Post
I've just put together a spread sheet for calculating L.E.C. (I know; its a guide not gospel) Is anyone willing to share any additional expansion values for things like strontium, or any other potentially useful ingredients, beyond what's listed in 'Modern Glass Practice' and 'Glass Notes IV'? Or have a suggestion of where to look for such additional values? Thanks in advance.
P.S. the original E&T values were published in 1927 in the Journal of the American Ceramic Society volume 10, pg. 551. It's a well written piece of history.
I've got Strontium down as 1.6 in the Appen Factors.

Appen plays out better for me than E&T, delivering estimates that look like the imaginary numbers I'm looking for and track ok with reasonable percent component changes. Lithium tracks better an Appen for me in particular.

Here's a bloc of numbers for common components related to the Appen estimates if you'd like to run your numbers through it. There's many additional oxides in the Appen list that I've excluded for simplicity. B2O3 requires a proportion subcalc but it's probably -.5 in SLS glasses. (I could be wrong. )

Oxide Molecular Weight Appen Factor
SiO2 60.08 / 0.38
Al2O3 101.96 / -0.3
B2O3 69.62 / -0.5
Li2O 29.87 / 2.7
Na2O 61.97 / 3.95
K2O 94.2 / 4.65
CaO 56.08 / 1.3
MgO 40.31 / 0.6
ZnO 81.37 / 0.5
SrO 103.62 / 1.6

"Calculating" is a strong word. It's an estimate, but it's an estimate that gives you something to think about relative to whatever other testing parameters you employ.
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