How to Polish Scratches on a Mirror

Functional mirrors help drivers steer clear of each other.

For the most part, mirrors -- particularly those used in automobiles -- are just panes of glass with a metallic coating on the back. Mirror scratches are no less common or more difficult to deal with than scratches in glass, but they are often more obvious because the reflective backing effectively doubles them. The solution to this problem is as old as the stained glass in the cathedrals of Europe.

Things You'll Need

• Abrasive pads, various grit
• Water hose
• Glass polish
• Microfiber detailing cloth
• Towel

Instructions

1. Arrange your pads in order of grit, going from most aggressive to least. You'll want at least four pads ranging from 120-grit to 1,200-grit. In the standard system, the pad colors are gray for 120-grit, maroon for 360-grit, light gray for 800-grit and white for 1,200- to 1,500-grit.

2. Wet the problem mirror and keep a hose handy. If you're removing scratches from an interior rear-view mirror, it's best and cleanest to remove the mirror from the car before beginning.

3. Fold the most aggressive pad -- 120-grit in this case -- in half and run it side-to-side across the mirror. Work slowly from top to bottom, always maintaining sideways strokes. Keep the mirror wet and move on when the pad starts to slide easily across it.

4. Use the 360-grit pad next, but this time turn the mirror sideways and use up-and-down strokes, perpendicular to the last set. This will take the "peaks" off the scratches you created with the first pad.

5. Repeat with the next-finest-grit pad, working side-to-side again, and finally with the finest -- 1,200-grit in this case -- working with up-and-down strokes.

6. Wash the mirror with water and either hand-dry it or blow it dry with compressed air.

7. Apply some specialty glass polish to the mirror according to the package directions.

Tips & Warnings

• This procedure should remove all but the deepest scratches and leave mirrors looking like new, but there is also a shade-tree approach to restoring even cracked and deeply scored mirrors. The basic idea is to use an oxy-acetylene torch to carefully heat the surface of the glass to about 1,500 degrees, causing it to liquefy and re-form with a smooth surface. You'll still have to polish it afterward, this time with a hard sanding board to get the surface level and smooth. This approach does, of course, require a very steady hand and experience with a torch, and getting some practice on an old piece of glass wouldn't be a bad idea. Be careful to keep the heat "shallow" and right on the surface of the glass; you don't want to overheat the metal coating or backing material.

References

• Auto Detailing: The Professional Way; James Joseph
• Evergreen University: 3M Scotch Brite Pad Colors and Grits