Firing different glass at the same time

Can I fire COE 90 and 96 in the same firing using the same schedule?

 In one sense this is the wrong question. The more general question is:

“Can I fire different glasses in the kiln at the same time?”

 Not all “CoE90” or “CoE 96” glass from different manufacturers have the same firing characteristics. This blog post compares the key temperatures for various glasses.

 For example, two glasses that are presumed to be “CoE90” have different published full fuse temperatures. Wissmach states its full fuse temperature is 777°C/1432°F and Bullseye states theirs is 804°C/1481°F. Both have an annealing temperature of 482°C/900°F.

 Wissmach 96 anneals at 482°C/900°F and Oceanside at 510°C/951°F. Wissmach96 has a full fuse temperature of 777°C/1432°F and Oceanside Compatible full fuses at 796°C/1466°F.

 Since annealing occurs over a range it is possible to anneal Wissmach96 and Oceanside Compatible together even though there is a published difference of annealing temperature of 28°C/50°F.  You could shotgun anneal – go very slowly from the soak at 510°C/951°F to 482°C/900°F with another soak.

 Fusing different manufacturers’ glasses – even if they are the same supposed CoE – is more difficult, unless you do not mind significantly different results.  Bullseye will full fuse at 804°C/1481°F. But Wissmach90 fuses at 777°C/1432°F. This will provide significantly different results.  The same for Oceanside and Wissmach96. The 21°C/38°F difference in full fuse temperature will provide lesser difference than the Bullseye Wissmach90, but will still be noticeable.

 This indicates that the full fuse effect of even the supposed same CoE will not be the same when fired together.

  

Finding the slumping temperature is determined less from the manufacturer than by observation. This post tells you how to find the slumping temperature.

 If these characteristics are similar, you can slump them at the same time. Expect some significant variation.

 There are some – possibly many – who will say firing different glass at the same time is both possible and successful. The manufacturers’ recommended temperatures show some wide variations. This makes it unlikely you will get the same desirable results for any but one of the glasses.

 My recommendation is do not try to fire different glass at the same time.  And why are you using two incompatible glasses anyway.