How To Repair Holes In Fiberglass

Posted on: 25 April 2016

Most cars have fiberglass bumpers for many reasons. First, fiberglass is strong yet slightly flexible, so dents can often be popped right out. Also, fiberglass is relatively easy to repair. With a basic fiberglass patch kit, you can fix small holes, dents and scratches. You can easily fix unsightly defects and maintain the structural integrity of the bumper. This article explains how to patch auto bumpers with a simple fiberglass patch kit.

What Comes in a Fiberglass Repair Kit

Fiberglass repair kits don't include everything you need for the job. They typically include the following:

  • Fiberglass cloth
  • Fiberglass resin
  • Hardening Liquid
  • Mixing Tray and Stick
  • Plastic putty spreader (or knife)

In addition to the kit, you will also need some other supplies. You might already own most of these supplies:

  • Painter's tape
  • Latex gloves
  • Scissors
  • Auto sandpaper (extra fine grit)
  • Power drill with wool buffing attachment

Patching The Hole

The first step is to prepare the area that you are going to patch by slightly sanding it. Just some light sanding will rough up the paint perfectly, so the fiberglass resin will stick better to it. Next, use the scissors to cut the cloth to the right size. The cloth should be at least twice as large as the damaged area. You want to make sure the defect is fully covered. Use the painter's tape to attach the cloth to the damaged area. Just put a little tape on each corner of the cloth.

Now you need to mix the resin with the hardener. Be aware that the resin dries very quickly once the hardener is mixed in. So, you need to be immediately prepared to spread it onto the bumper. The hardener tube will tell you how much to mix into the resin.

Use the putty knife to spread the resin onto the cloth. Once you have enough resin on the cloth to hold it in place, you can start to remove the tape. As you spread the resin you want to fully cover the cloth and overlap the edges. You don't want any cloth texture to be noticeable. You might need to apply two coats to get full coverage.

 Finally, you need to sand down the patched area once the resin is completely dry. Then, to polish the surface so it has a sheen that matches the original bumper texture, you need to use the buffer. With a power drill, a simple wool buffing attachment can polish the patch in no time.

If you feel you cannot do this alone, visit a collision repair shop, such as Accurate Auto Body, that can fix your hole using professional tools.