Slumping Pyroceramic Glass?

[weo]

Hello all. Outdoor Gear Dad's thread question on glass platens reminded me of a project I started to make a glass platen with a 3' radius for hollow for a urasuki on my chef's knives. I've had the radius-ed piece of O1 tapped for my grinder and the piece of glass sitting next to it for a couple of years now. A search brought up these two threads:
https://bladeforums.com/threads/ceramic-radius-platen.1581979/
https://www.bladeforums.com/threads/slumped-glass-platen-is-it-possible.985289/

However, neither of them posted conclusions. So, my question: @JTknives, @Fred.Rowe, (or anyone else who's tried this) did you finish this, was it successful and is there a 'recipe' for doing this in my Evenheat or Jen-Ken kiln?

 

[Tenebr0s]

I'd love to know too. My understanding is that you cannot slump pyroceramic glass without ruining its properties, but you *can* slump borosilicate glass. The trick is getting the right cooling rate to prevent devitrification, which means a fairly fast cooling rate from its slumping temperature to its annealing temperature and then a slow cooling rate from there. I have read that a thin coating of borax (dissolved in liquid, painted on and dried) can be helpful. I meant to try this a while ago and never got around to it.