Someone long ago installed a tinted window film on the rear window of my 58 triumph 10 sedan (saloon), I can’t ctrape it off for fear of damaging the rear window demisting strips and it doesn’t respond to heat or water, what will remove it?
Spray the window tint with amonia . Cover the window tint with black garbage bags. Point the rear window towards the sun so the garbage bags get hot and the amonia dries. Remove the garbage bags from the window and the tint will come off with the garbage bags.
A '58 Triumph has demisting strips? Probably installed by the same person who tinted the window.