I don't want to go beyond the epoxy, but I wanted to get the epoxy smooth - and eliminate the pits that still have ablative in them. It seems to be the process of eliminating the orange peel finish in the epoxy that is dulling the sanding discs. I suspect there is a point where I have enough of the ablative off that I can apply another coat or two of the Interprotect over everything, and it should be easier to sand when it is still fairly fresh as opposed to having had a couple of years to cure.