For hazy, clouded and dull plastic windshields that look beyond hope there is a trick that sometimes works to restore them to almost new condition. I am not sure why this works on some windshields and not others, but when it works the results are amazing.
Get a roll of wide clear packing tape and lay down strips smoothly across the surface. Fold over the end of each strip so you have a handle to remove it with. Rub the tape smooth with your finger and then as you peel each strip off, if you are lucky, the oxidized surface will lift off with the tape leaving an amazingly clear finish. This neat trick has restored a lot of windshields that we would have previously thrown out. Since this works on some but not all hazy shields, I suggest you test on a small inconspicuous area of the windshield first.
Some haziness and scratches in windshields can also be treated with a scratch removing polish, followed by a coat of wax.
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