I am getting ready to slump and oval platter 12" across by 9". Right now it is 3 layers thick about .300 and I have a 1/4" overhang. I have never slump with an overhang do you think this is too much of an overhang and that I should cold work it and get it down closer.
One rule of thumb is that an overhang that is the same dimension as the thickness of the glass is OK. You can stretch it a bit more with pretty good luck.
I always try to get the job done with lower temp and more time, until impatience sets in and I bump up the temp to get it over with...