COE 104 Questions
 

I'm pretty new and have a couple of basic questions.

1. If I buy COE 104 glass from different sources, is it OK to mix the glass?


2. After I make the bead, how much time should I spend cooling down the bead (in cooler parts of the flame) before putting it into the kiln? I think I may be spending too much time on that part. After the bead stops glowing is it safe to go ahead and put it right into the hot kiln at that point?

Thanks!

1. Yes, for the most part, some even though it is the same coe is incompatible

2. None, yes to the second

COE means "coefficient of expansion" and is a scientific term. Rule of thumb is plus or minus 2 numbers and it's OK to mix.

I don't mix Lauscha or Czech glass with Effetre except in tiny amounts, such as stringer decoration. I mix Messy and Effetre with caution and also generally in small amounts. Some colors like the moonstones are fussier than others about mixing. I rarely encase Messy color except tiny amounts because I don't like their clear.

Uroboros 104 clear seems to get along well with everything.

Put your bead in the kiln as soon as the glass stops moving. Glowing is good, you just want to be sure it is firm enough not to sag.

1) Although in theory all 104 glasses should be compatible, in practice it is not always the case. Glasses with the same COE but very different viscosities can lead to compatibility problems. And even in the same brand, not all colors are always exactly 104 and some color combinations can get you into trouble. With Effetre for example, opaque yellows do not mix well with transparent cobalt blue.

2) The way I teach my students is to stabilize the bead outside the flame for about 20 seconds (less if it wasn't really hot at heart) then pop it back into the back of the flame until you see a very slight red glow that disappears as soon as you take the bead out of the flame. This way you know the bead is hard and the heat isn't deep but it isn't too cold and hasn't been shocked.