question about COE

[glass_noob]

I was just wondering which types of glass can be used with boro?? and what exactly COE is and which numbers are compatible. any feedback would help greatly..

[Greymatter Glass]

For details on COE read this:

http://en.wikipedia.org/wiki/Coefficient_of_thermal_expansion

In glass we refer to the most relevant figure of the expression:

α = 3.3 x 10^-6/C at 20 °C

α is the greek symbol alpha, used to denote a percentage of expansion.

We refer to Boro as a 33 COE or 3.3 COE (in the case of 33 coe it would be 10^-5)

In laymans terms it's the amount the glass expands as it heats. Only glass with a very similar α will be compatible in the range of boro. I generally consider 32-34 in the safe zones with proper annealing.


COE is not the only factor however - viscosity and the fact that in glass expansion isn't really linear play a role. the insulating properties combined with chemical composition (density, viscosity) will affect the speed and point at which the glass will be expanding/contracting in some part.

That said, the COE of clear boro and the "compatible" colors are well tested and should usually cause little trouble if used according to the manufacturers advice. The only glass that can be used with boro is glass made to be compatible. With the exception of some exotic glasses for sealing to metals and various technical applications the only glass that's compatible with boro would be other 33 expansion borosilicate glass.

Cookware, coffee mugs, Corningware, and most other consumer glass is not compatible with what we do.

-Doug

[Granger's Glass]

COE stands for coefficient of expansion. If boro has a COE of 33 that means it expands 0.000000033% when the temp of the glass goes up 1 degree centigrade. I don't know what you mean when you ask what different types of glass can be used with boro. If its COE is 33 +/-1 it should be compatible. A glass called moldavite can be used with boro. I have used two pieces once. They are not that cool. Synthetic opals can be incased in boro as well. Most online stores have them. This site has the best selection. >> click!! (http://profoundglass.com/current_gilson.html)

[Granger's Glass]

:twitch: ahhh Doug beat me to it

[glass_noob]

ty for the knowledge i was just wondering that cause i have some 104 COE dichro on ripple black and i was wondering if that is soft glass or if it was compatible with boro

[Greymatter Glass]

that is soft glass, compatible with moretti

[glass_noob]

ty i dont really know all to much as i am self taught so this website has been the most awesome tool in the artillery lol

[x947]

when you buy and use frit, do the same issues apply ? It doesn't seem like I see COE numbers on frit . . .

am I just missing them ?

[Jones Art Glass]

Yup, Theres Def a difference in frit as well... Theres frit made for most types of lampworked glass so be careful just ordering stuff ya'll. Always ask for boro! (when working boro of course..)

[Greymatter Glass]

BAT JONES!

yeah, but with soft glass frit you can get away with a lot more range for some reason it seems....punks.