We bought a used car recently and the windshield has a faint remnant of that glass chalk/paint that they use to write stuff on the windshield with. There's just enough of it remaining on the windshield to be distracting, and we've been trying everything we can think of to get rid of the stuff.
So far we've tried -
Windshield washer fluid
vinegar and baking soda together (fizz, fizz)
...and it still persists. Any suggestions?