Question on COE

[dulceisler]

I understand that you cant mix one COE with another (including frit right??)

...but what does it represent? Is it better to get 96 COE or 104 COE glass - I also saw on that annealing chart 33.2 as a COE.... Is one better to make beads vs. small figures? etc. Any help would be great!!!!!

:grin:

Thanks Dulce

[tiggybubba]

coefficient of expansion...
how quickly it expands and contracts as it heats and cools
has nothing to do with bead size...

[FiredDesires]

When mixing glasses you not only have to take the COE into account but its' viscosity too. It is recommended not to mix glass with varying COE's more than 2-3 points apart. Sparingly on the surface you can get away with using/mixing COE in varying degrees as a glasses lead content allows for more margin of error. I know, i know...you just want to do glass not become a dang chemist! lol Don't we all?

Just because something has the same COE doesn't mean that it would be compatible. A good example? Moretti glass..COE 104 and its' alabastar or opalino glasses...even in a family.. not all brothers & sisters get along!

I don't know where it is, but a couple years ago I started a glass COE listing of what glass was what, folks have added/adjusted & the result is a listing that would be handy for you to have, anyone who has the link...help D out would ya?

Information of interest for you: The higher the COE the more fluid the glass will be, the lower the COE...the stiffer the glass. Satake COE 113-121 is very soupy & soft. Bullseye Glass COE 90 is stiffer than Moretti/Effetre COE 104. Boro glass, which is a hard glass is very stiff working with a COE of 31-33 (COE of boro can vary a couple of points, clear vs. color)