Marcus… Thanks for posting the link. try using a heat gun or a torch to blow hot air over the silicone after the bubbles rise for a while. That will cause all the bubbles anywhere near the surface to pop instantly. I’m not sure how deep it will reach though. Next time I refurbish a set of trays I’ll try one with just the heat gun and report back if that is sufficient or not.
There’s also a link somewhere in these forums that suggests that applying RainX to the silicone lengthens the life of the trays. I haven’t verified that one myself yet.