Remove Rust

• 1). Brush away rust with a wire brush. If the rusted area is large, attach a wire brush drill bit to a power drill to remove the rust.
  
  
• 2). Wipe the surface with a rag to remove the bits of rust.
  
  
• 3). Sand the metal with silicon-carbide sandpaper. Begin with coarse-grit sandpaper, and progress through the grits to extra-fine grade. Progressing through the grits means using coarse-grit sandpaper, then medium-grit, then fine-grit and finally extra-fine-grit sandpaper. Using a variety of grits ensures a smooth finish.
  
  
• 4). Dampen a rag with isopropyl alcohol and wipe the door frame to remove the sanding dust.
  
  

Repair Dents

• 1). Sand the paint off the surface of the dent, plus 1 inch to 2 inches in all directions, using coarse-grit sandpaper.
  
  
• 2). Apply epoxy filler with a stiff metal putty knife. Firmly press the filler into the dent and build it up to 1/8-inch higher than the frame surface.
  
  
• 3). Allow the filler to dry completely --- generally one to four hours, depending on the thickness of the filler.
  
  
• 4). Sand the putty flush with the existing door frame. Begin with coarse-grit sandpaper and progress to extra-fine-grit sandpaper.
  
  

Repair Holes

• 1). Sand the edges of the hole to smooth them, and remove any rust or corrosion with coarse-grit sandpaper. Sand a 1-inch surface around the hole to remove rust, oils and old paint.
  
  
• 2). Apply epoxy filler with a putty knife to create a 1-inch border around the hole.
  
  
• 3). Cut a piece of fiberglass mesh screen 1 inch larger than the hole in all directions. Press the screen into the epoxy filler firmly. Allow the filler to set for 30 to 45 minutes.
  
  
• 4). Apply epoxy filler over the fiberglass mesh, building it up to slightly higher than the steel frame surface. Allow the filler to dry thoroughly, typically between one and four hours.
  
  
• 5). Sand the epoxy filler flush with the existing surface, beginning with coarse-grit sandpaper and working your way through the grits to extra-fine-grit sandpaper.
  
  

Painting

• 1). Sand the door frame with medium-grit sandpaper to remove old paint, grease and dirt. Sand with fine-grit and finally extra-fine-grit sandpaper. Use a sanding block or an orbital sander to strip the steel.
  
  
• 2). Wipe the door frame with a rag dipped in isopropyl alcohol to remove all sanding dust.
  
  
• 3). Apply a coat of rust-inhibiting metal primer with a paintbrush. Allow the primer to dry fully, usually two to four hours.
  
  
• 4). Apply two coats of rust-inhibiting paint, using a paintbrush. Allow each coat to dry completely between applications.