How to Use Bondo in Repairing Holes in Metalby G.K. Bayne
Using Bondo in repairing holes in metal is a skill that all auto repair shops perform daily. If the holes are not too large (smaller than your fist), a single weekend is all the time required for repairing a hole in metal. The most difficult part of the project may be finding the proper color to match the paint.
Attach the 180-grit sandpaper to the orbital sander and remove the paint from the surface around the hole. Bondo will not adhere sufficiently to a painted surface. The sanded area should be about 1 to 2 inches around the hole.
Apply the Bondo to the area to be repaired in layers with the supplied Bondo plastic knife. Each can of Bondo comes with a plastic applicator knife. The thinner the layer, the faster it will dry. If you apply the Bondo too thick, it will be more difficult to remove with the sander. Be sure each layer is applied in a smooth coat and that no large ridges are left on the surface.
Allow each thin layer to dry before lightly sanding the area between coats of Bondo. The dry and cure time on the Bondo will depend on the weather--the drier the day, the faster the cure time.
Sand the final layer of Bondo so it is as smooth as the surrounding metal. There may be small scratch imperfections in the surface, but you can touch these up with thin coats of Bondo.
- check If the Bondo falls through the hole, a piece of cardboard can be placed behind the hole to back up the Bondo.
- check Wetting the surface lightly with water to final coats of Bondo will aid in a smoother finish.