Bought a car 2 weeks ago, and someone in their wisdom decided to apply either intentionally or not, wax to the windscreen! (before my purchase) - looks maybe like an accidental runoff ?

Anyway, every time the wipers wipe I see a "scum" on the windscreen, but after the wipe the screen is clear. My problem is that whenever the wipers are on constantly this "scum" is there, and it would worry me if it was raining at night and my vision would be affected.

I have tried household glass cleaner, water and vinegar, cleaning with newspapers. Bought some foamy type stuff "that will clear anything" according to the chap in the motor factors (have bad news for you buddy!). Got some stuff off the chaps at Autoglass, have even tried the old trick of the potato cut in half smeared over the screen, all to no avail...

Apparently nail varnish remover (or something with Acetone) may lift it. Unfortuneately the only nail varnish remover in our house is acetone-free! Have to hunt some out.

Does anyone else have any tips worth considering? Before I accidentally hit the screen, causing that nice young chap from Autoglass to replace it!
(Its not the wiper blades themselves either - have changed those)

Its a real pet hate of mine having a screen which isnt clear!