My first schedule, in an early post, failed similarly. So I tried again with your suggested working temp:
300 dph 1450 hold 10
9999 dph 900 hold 60
50 dph 700 no hold
I have run the know your kiln tests and my kiln fires very evenly. And unless my pyro has gone bad, I have never had any trouble with over firing.
My glass production dates are:
1009 - 10/15/09
0216 - 7/02/10
This is a photo of my layup: (The other test on the right has reactive irid on clear with the irid in the same orientation as on the cyan so I can see if I got the correct side down after firing.)
This is the top after firing:
This is a close up of the bottom so you can see the irid is on the correct side: (sorry for the hot spot, but it helps you see the irid sparkle a little better in the clear. The sparkle on the cyan is just regular sparkle
. you can see the irid a little better on the bottom right corner. ).