Another tip I can pass on to maybe help is to use an aerosol high alcohol content glass cleaner before the glass polish
Autoglym do make one but it's hard to find as most shops just stock their Fast Glass which is pretty poor and no better than a household glass cleaner, smears quite badly and takes a lot of elbow grease to get the residue off
All my professional glaziers use an aerosol glass cleaner and paper towels rather than a cloth - much, much better and quicker and cuts through any build up on the glass
