Sunday, December 10, 2006

VW - Polishing Glass

A Shy Person asked:

>Got a question on windshields. Mine is in pretty good shape as far as nicks, chips, smokey corners go, but it does have a lot of fine swirl type scratches in it. Maybe from being washed so many times? Anyways, is there a way to refininsh the surface?


Dear Shy Person (and the Newsgroup),

No problem. Get yourself some cerium oxide and a felt polishing hob. Make a mixture of cerium oxide & water having the consistency of light cream. Paint it onto a small area of the glass and buff with the felt hob mounted in a low-speed drill motor. Keep the stuff damp -- spritz on more water and add more polishing compound as needed. Dry and buff with a soft cloth, inspect the surface with a loupe of at least 5x (look for tiny 'rainbows' -- refraction from microscopic pits & scratches... if you do a good job, you won't see any). Takes about 20 minutes to polish an area the size of your palm. But worth the effort.

You can get a 'kit' of cerium oxide & polishing hobs from J.C.Whitney. Cheap.

Stantium oxide cuts slower than cerium oxide, gives a finer finish. Ferrous oxide, the red stuff -- and often called 'rouge' for that reasons -- cuts slowest of all, gives the finest finish. But rouge is messy as hell and ferrous oxide can react with rubber & trim.

Polishing the windscreen is a standard procedure for vehicles that accumulate a lot of mileage -- buses, trucks and the like. But if the scoring isn't too bad you may not need to polish -- you can get rid of the refraction problems by filling minor scratches with black wax then buffing the glass smooth. This only works if the scratches aren't too deep.

Rain-X also reduces the effect of light-scatter caused by scratches but a layer of Rain-X can prevent the polish from working so try that last.

-Bob Hoover

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