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hypothetically , if a project was not sufficiently annealed, is it possible to reheat to anneal temp and redo the anneal ?
thanks Stef

Shouldn't be a problem. Just go really slow on the heat up. Then use your regular schedule for finishing the firing.


Joe

25 degreesC (77F ) be slow enough?

how big? How thick? full fused or tack fused?

No easy answer to that question.

Good Luck

Don't forget to go above anneal and hold for abit before you go back down to anneal to make sure the inside of glass is same temp for even anneal. (I have taken a larger piece back up to 1100 F. but because it was an inch thick I went toooo quickly and broke it, THEN went 50 deg per hour back up to full fuse and it all went back together so nicley), so slow down to 50 deg. per hour just like suggested above and it will help to even heat everything as well. Les

1/2"(12mm) thick,
12" ( 30cm) round.

Slump ( into sand) prog was:
Farenheit;
300/1000/20
570/1380/60
AFAP/1000/45
75/970/90
75/900/15
130/750/10

Celcius;
150/540/20
300/750/60
AFAP/540/45
25/520/90
25/485/15
55/400/10

I thought this ramp down would be slow enough to anneal but seems not.
2 of the discs seem fine, 1 has broken through the centre while I was scrubbing the sand off it, 1 is still in the kiln on the sand so I thought I might try taking it up again and adding an extra hour soak at 900 (485)
So the questions are ...
how fast to go up ( to 1000(540) )
and am I ramping down slow enough
Am I soaking at the right temps??
cheers Stef

Here are the suggested firing and annealing recommendations from System 96:

http://www.system96.com/Pages/ThickFiringGuideF.html

I would follow the 1 inch recommendation since you are firing on the sand bed.

Barb

thanks Barb,
that makes sense... my thinking was stuck in a groove... I thought I had the correct firing prog from when I did this about a year ago but I must have lost the right page with the longer program from my folder. It just didn't connect with my brain that the anneal soak was too short.
(Note to self; ... tidy folder & studio.)
Now I need to re anneal the discs which haven't broken.
Any idea on how fast/what temp I should reheat at ??
Any advice from anyone is much appreciated.
stef
I have tried to upload a photo of what I am doing but It tells me that the file is invalid... What does that mean?
I'm not very clever with computers!

I'd go up at 50 dph (or slower) to 1000 degrees, then come back down through the recommended annealing schedule... Good Luck!

Barb