Over Annealling

[Judd]

I was experimenting with a new pattern bar technique. It was late at night, I was tired... bla bla bla...
So. I programmed in a 9 hour anneal and hit the fire button.
I checked the next morning. Looked good. That evening, I checked again but didn't look at the digital read out, but it seemed to be acting normal.
The next morning... hmmm? That evening I knew something was wrong, and I reviewed the schedule.
Ugh... instead of a 9 hour anneal, I had programmed in a 90 hour anneal. It was on hour 36.
Crap.
So, I advanced my program to the cool down and went to bed.
So... opinions please. This was 96 COE glass. This pattern bar is toast, right? I can cut it, put it into a plate, but it's going to crack because of COE/ viscosity shift, right?

Please don't lecture me about checking my programs. Yeah yeah yeah. I know that. I screwed up. What about the glass?

[Judd]

And a second L? Ugh...

[Tony Smith]

I think you'll be fine... There should be minimal changes to the glass by holding at the annealing temperature for a long period. Now if you held a fusing temperature for such a long period, I would expect some adverse effects.

Tony

[Morganica]

You're a WHOLE LOT better off than if you'd programmed in a 9-minute anneal soak...

Seriously, you're at 4x your planned anneal soak. Unless your kiln is way off on temps and full of hotspots, so that the air around one side of that pattern bar was maybe 20 degrees cooler than the air around the other side and STAYED THAT WAY long enough for a serious temperature differential to build up inside the center of the bar as it slid under the strain point, I wouldn't worry about it.

The viscosity/compatibility shifts, if any, would be a function of spending far too long at process temps, and that's got nothing to do with the anneal soak (as Tony says, now if you'd spent 36 hours at PROCESS temps... ). Any annealing problems will show up fairly quickly when the wet saw starts in on the bar. If they do, just stop cutting, throw the bar back in the kiln and take it up to about 1100F (slowly). Hold maybe 30-40 minutes, then anneal as you'd planned. It should be fine.

[Bert Weiss]

The longer you hold your glass in an environment, the more the glass will reflect that environment. So, if the temperature the glass sees is within 5ºC, annealing should be fine. If the temperature inside your kiln varies by more than 5ºC, the longer you hold, the more the glass will have that differential in it as well. The areas you have to be concerned about are the difference between the center of the kiln, and the walls. The closer the glass is to the walls, the more likely there is a differential.