Quoted from Wickerman2:
What game? Older EM’s sometimes benefit from some triple thick on the back to keep from flaking
All my EM's get a coat of Triple Thick either to preserve or part of the process of doing touch up to glass that is starting to flake apart.
First solid state I have done was a Ball Star Trek which had a bad reaction to the triple thick that caused it to wrinkle like crazy where the sealer had been sprayed. Lucky the damage was confined to those sections that I was trying to lock in that had already peeled and cracked and I was trying to save them. If I had done the whole glass I would have been left with a ruin.