Repairing body parts with fiberglass

Parts of body rusted cars are commonly repaired with fiberglass, which is a material for repairs very durable. Repairs with fiberglass layers consist in reinforced material in which is placed catalyzed resin. Fiberglass adheres to almost any material, including metal, plastic and even some types of porous wood. These repairs will last as long as the rest of the body if done correctly. All materials needed to make a repair with fiberglass can be found in stores or local bodies supply stores.


  1. Put on safety glasses and mole any rust metal surface. Clean the surface that must be repaired with a damp cloth with acetone and make sure that all damaged and rusted metal is removed.
  2. Torn pieces of fiberglass mat to replace the rusty metal that you deleted. Use as many layers as necessary and do each layer bigger than the previous tear 1/4 (0.64 cm) inch.
  3. Mix a batch of resin in a small cube adding two thirds of catalysts.
  4. Moisten the surface of the repair area with the resin using a roll of 4 inches (10.16 cm) of felt. Apply the smallest mat first layer in the center of the repair and saturated with resin using a roll of felt. Apply a roller air to the flat layer and remove any air trapped beneath it. Apply the next lower layer and repeat the same process. Continue the same procedure for each layer until the repaired area reconstructs a homogeneous area with the surrounding metal. Let fiberglass cure and harden at least one hour.
  5. Wear a respirator and sand surrounding the metal fully repair using a hand sander with sandpaper of 220 grain. After you have sanded with 220 grain sandpaper, re-sand with 600-grit sandpaper to leave completely smooth.

Tips & Warnings

  • Fiberglass hardens within 20 to 30 minutes after catalyze so you should work at a fast pace.
  • Always use a respirator when sanding materials of fiberglass.