A dent in a steel garage door can be fixed in much the same way as fixing a dent in automobiles or other steel doors. Small dents might be pulled out with a standard automobile dent puller. This is a suction-like plunger device that attaches over the dent, and the dent is literally pulled out. Although this might work adequately for smaller dents, larger and/or deeper dents will need to be fixed in a completely different fashion.
Things You'll Need
- 80- and 150-grit sandpaper
- 400 grit wet/dry sandpaper
- Rubbing alcohol or acetone
- Soft cloth
- 2-part automotive body filler
- Putty knives, one for mixing and one with a plastic 6" blade
- Rubber sanding block
- Rust inhibiting primer
- Masking tape
- Paint brush
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Sand the dented area with 150-grit sandpaper. All of the paint must be removed and every crack and crevice must be sanded clean.
Dip a clean soft cloth into rubbing alcohol or acetone, and wipe the area off thoroughly. This will remove any grease and left-over sanding grit.
Blend a two-part body filler together. In most cases you will be using equal parts filler and hardener, but different types may have different ratios of hardener to filler. Consult the manufacturer's direction for the proper ratio. Mix the filler and hardener on a paper plate, piece of cardboard or other medium. Mix them together with a small putty knife.
Spread the body filler into the dent with a plastic 6-inch bladed putty knife. Smooth it out as best as possible, and slightly overfill the area to account for product shrinkage. Allow the patch to cure completely. Test it by scratching the top of the filler with a fingernail. Properly cured filler with leave no mark when it is scratched. Deep dents will require two applications of filler. Feather the sides to blend in with the rest of the garage door.
Sand the patch to smooth it out by first using 80-grit sandpaper on a rubber sanding block. Sand with the 80-grit sandpaper until all of the high spots have been removed. Switch to 150-grit sandpaper to finish-sand the patched area.
Mask the area with sheets of newspaper and masking tape. This will ensure that only the dented area will be covered by paint.
Apply two coats of rust inhibiting primer onto the patched area with a paint brush. Allow the first coat to completely dry before painting on the second coat. Allow the second coat to dry.
Wet-sand the primer with 400-grit sandpaper which has been wrapped around a sponge. Dip the sponge into a bucket, a sink or run water over it with a hose. 400-grit wet-sanding will turn the primer into a glassy smooth surface. Allow to dry.
Paint the patch with a high-quality enamel paint. Many garage doors come in standard colors which can be obtained from hardware stores or automotive supply shops. Apply two coats, allowing the first coat to dry completely before painting on the second coat.