How to Sand Exterior Paint

Select the appropriate sandpaper grit for each job.

There are a variety of reasons why an amateur do-it-yourselfer might need to sand exterior paint. First, glossy paint is not conducive to adhesion, so it must be abraded with sandpaper before new paint will stick. Second, stubborn old, loose and peeling paint that resists scraping can be eliminated with the help of a palm sander. Finally, if you want to completely strip paint from a surface, you can use sandpaper to complete the task. However, before you get started on any of these tasks, you need to select the correct type of sandpaper grit appropriate for each job.

Things You'll Need

• Pressure washer
• 400-grit sandpaper
• Tack cloth
• Metal putty knife
• Palm sander
• 120-grit sandpaper
• Paint stripper
• Plastic putty knife
• 3- to 4-inch oil-based paint brush
• 80-grit sandpaper

Instructions

Promote Adhesion

1. Clean the exterior paint using a pressure washer. Allow the surface to dry.

2. Abrade the glossy exterior paint to promote adhesion by sanding it with 400-grit sandpaper. Do not over-sand. Stop sanding when the glossy exterior paint feels rough to your fingers.

3. Wipe down the exterior paint with a tack cloth before you apply a fresh coat of paint.

Remove Old Paint

1. Remove as much loose or peeling paint as you can by focusing concentrated water pressure using a pressure washer. Allow the surface to dry.

2. Scrape away remaining, large pieces of peeling paint using a metal putty knife.

3. Sand free any smaller, stubborn bits of old, chipping paint using a palm sander loaded with 120-grit sandpaper. Sand with the grain of the wood and never against it.

Strip Paint

1. Apply paint stripper to the exterior paint using a 3- to 4-inch oil-based paint brush. Allow five minutes for the stripper to loosen the paint.

2. Scrape loose the paint using a plastic putty knife.

3. Apply more paint stripper using the paintbrush, then sand off any remaining paint using a palm sander loaded with 80-grit sandpaper.

4. Work the edge of the sandpaper into crevices and grooves to strip paint from stubborn, hard-to-reach areas.

5. Rinse the surface with a pressure washer.

Tips & Warnings

• Never sand against the grain of wood, or the surface will splinter.

• A pressure washer can damage wood. Be sure to begin the washer on a weak setting and gradually increase pressure, or you may damage the surface.

Resources

• Popular Mechanics: 5 Pro Painting Tips Every Amateur Should Know