When Should You Polish Your Windshield?

Sometimes road film or water spots will not come off with glass cleaner. That is when you may need to physically polish the exterior glass by hand or machine. If the baggie test reveals bumps, clay the glass first.

Check the Glass

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Quick Answer

Polish When Glass Cleaner Won’t Remove the Film or Water Spots.

Start by getting the outside glass absolutely clean, then do the baggie test. If you feel tiny bumps, the glass needs to be clayed. If it feels smooth but still shows road film or baked-on water spots, polish to remove what is bonded to the surface.

Know When to Polish

Three Common Reasons for Polishing Windshields

Removing scratches isn’t necessarily the most common use case for polishing a windshield. Most of the time polishing is done to remove bonded contamination that can’t be removed chemically.

Baked-On Water Spots

Fresh water spots may come off with glass cleaner. Hard water spots that have baked on normally require mechanical abrasion with a dedicated glass polish.

Bonded Road Film

Road film is oily dirt splashed up from the road. Once it has built up and bonded to the glass, it may not wash or wipe off with glass cleaner.

Glass Coating Preparation

Before applying a glass coating, polishing helps you get down to pure bare glass so the coating can make a strong bond.

Free Printable Decision Tool

Should You Clean, Clay or Polish?

Use the Windshield Polishing Decision Guide to identify what bonded contaminants are on your glass and follow the corrective steps in the right order. This guide will help you:

Use the baggie test to determine whether the glass needs clay

Decide whether to clean, clay, hand polish or machine polish

Know when polishing will not solve the problem

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