So started peeling this off a window and half of the film has come off but the rest is stuck and its really difficult to remove.
Is there anything i can spray on there that will eat away at the film so i can get it back to glass easily?
This is extremely difficult, if not impossible, to do. We bought a house that had UV film on four sets of large aluminium bi-fold doors and side panels. It was about 15 years old and had gone milky and had to come off because it was blocking the main view from the house. This was about 15 sq. m. of glass in 10 panels each about 2.2 m high.
I spent months googling, researching, phoning people (applicators, chemical companies like Selleys, film manufacturers like 3M etc). I tried every chemical, aerosol, solvent, temperature and physical scraper combination known to mankind - and just could not get the stuff off. With great difficulty I could get some of the film off in very small pieces but the adhesive, the component causing the milkiness, was still there. I spent a small fortune on all this but it was a complete WOFTAM.
Gave up and got three quotes for complete replacement of the safety-glass with UV built-in. Didn't cost an arm and a leg - the installer did an excellent job simply and quickly - and we got a crystal-clear result (as you would expect with new glass). I found huge variations in the quote prices so it pays to shop around if you take this approach.
Sometimes I just sit and think. Other times I just sit.
OP, just to be clear, are we talking about a car or a house window? The answer to your question depends on this or, to be more precise, the type of adhesive on the film.
This is a House window.
I did get eventually it off, well I have done 1 panel. It took a couple of hours, I need to do a whole heap more done though :(. I didn't have any acetone.
Ended up buying a brand new razor scraper which was much better than the old blade I had, which helped a LOT. I sprayed it with ammonia. But yeh doing a whole house would suck mega hard. I need to do 3 more then im done with this job.