Metal objects with rust, dents or a damaged finish can usually be repaired unless they are badly deteriorated.
Chipped paint or scratches on a metal surface are often the easiest to fix. A simple scratch can be repaired using appliance touch-up paint. Sold by appliance dealers and repair stores in a variety of colors, touch-up paint comes in a small bottle with a brush in the cap. Apply several thin coats to a deep scratch.
For more extensive surface damage, sand away rust and loose paint with fine-grit sandpaper. Brush off the dust, then wipe the area with paint thinner. Apply a thin coat of rust-inhibiting metal primer. After the primer dries, sand it lightly with extra-fine grit sandpaper.
Select an enamel spray paint specified for metal. Then make a mask from stiff paper or cardboard by cutting an irregularly shaped hole, slightly smaller than the primed area. Hold the mask about six inches above the surface and move it in a circular motion while spraying through the hole. This will feather the edges of the paint and make the repair less apparent. Apply two or three thin coats rather than one thick coat. Test your spraying technique on a piece of scrap first.
Remove loose particles of heavy rust with a wire brush or a wire wheel on an electric drill. Then sand with coarse sandpaper until the metal is shiny. Wipe the metal with paint thinner. Then prime and paint.
Instead of sanding away rust, you can also use a liquid rust converter available at hardware and auto-supply stores. Remove any loose rust, then paint or spray on the converter. It hardens and seals the remaining rust, creating an irregular but rustproof surface that you can prime and paint.
Dealing With Dents
Sheet metal is especially subject to dents, but they can usually be straightened.
If the metal is fairly thin, try pushing a dent out from the back with the heel of your hand or by lightly tapping it with a mallet. If that fails, press a bag filled with sand against the front of the dent and tap back gently with a mallet.
You can also press a dent out with a carved block of wood. Using a knife and a rasp, shape the end of a short piece of wood to fit the internal curve of the damaged area. Clamp the shaped wood in a vise and gently rub the interior side of the dented area against the wood until the metal surface is smooth.
You can also hold the face of a small sledgehammer or dolly block (a polished steel block available at auto-supply stores) against the dent. Lightly strike the raised side of the dent with the flat face of a ball-peen hammer or an auto-body hammer.
If the object is painted, you can fill dents or even rust holes in thick metal using a fiberglass repair kit from an auto-supply store.
Follow the kit's directions carefully. Here is the basic procedure: Drill a series of small holes in the affected area to help anchor the fiberglass filler. Clean and sand the metal, especially rusted areas. Prepare the filler. Use a putty knife to apply filler to the holes around the dent or the rusted hole. Press the filler in and around it a bit above the surface. Overlap the edges of the undamaged area.
Let the filler cure completely. Then use a sanding disk in your electric drill to smooth the filler even with the surrounding surface before priming and painting.