Table of contents: Repair of minor scratches in the… ↓ Repair of dents in the body structure ↓ Repair of rusted holes or punctures ↓ Priming and painting ↓ Plastic parts ↓
Note: For more detailed information on body repair, see the book "Body Repair Guide".
Repair of minor scratches in the body structure
If the scratch is superficial and does not penetrate to the body metal, the repair is very simple. Lightly wipe the scratched area with a special compound to remove the peeling paint. Rinse the damaged area with clean water.
Apply car paint to the scratch. Continue applying thin coats of paint until the paint level in the scratch is equal to the paint level around it. Let the new paint dry for at least two weeks, then polish the surface. After that, wax the scratch area.
If the scratch is deep and the body metal has begun to rust, use another repair method. Use a pocket knife to remove all the rust down to the base of the scratch, then use a primer to prevent future rust. Using a nylon brush, coat the scratched area with filler. If necessary, dilute the filler to create a paste that will fill narrow scratches well. Before the filler hardens, wipe the surface of the scratch with a thinner filler. This will ensure that the surface being repaired is just below the level of the surrounding paint. The scratch can now be painted as described earlier in this section.
Repair of dents in the body structure
When restoring dents, you should first level the surface as close to the original shape as possible. There is no point in trying to restore the original shape, since the metal in the damaged area will be deformed and will not be able to be brought to the original contours. It is better to make the dent level 3 mm lower than the metal around it. In cases where the dent is very shallow, this should not be done at all. If the back of the dent is accessible, it can be straightened out easily with a straightening hammer. When doing this, apply a wooden block to the opposite side of the dent to absorb the hammer blows and prevent deformation of the metal.
If the dent is in a double-layered section of the body or is otherwise inaccessible, try the following method. Drill several small holes in the metal inside the damaged area. Drive self-tapping screws into the holes to get a good grip on the metal. The dent can now be pulled out with pliers, pulling on the protruding screw heads.
The next stage of the repair is to remove the paint from the damaged area and for 2.5 cm around it. This is easily done with a wire brush or an emery wheel clamped in an electric drill. This work can also be done effectively by hand with sandpaper. To finish preparing for priming, scratch the surface of the metal with a screwdriver or file. Or drill small holes in the area to be treated. This will ensure good adhesion of the filler material. To finish the repair, see the section Priming and painting.
Repair of rusted holes or punctures
Remove all paint from the surface to be treated and for 2.5 cm around it using a wire brush or an emery wheel clamped in an electric drill. This operation can also be done effectively by hand with sandpaper. After removing the paint, determine the severity of the damage and decide whether to replace the entire part or repair the damaged area. New body panels are not very expensive and it is often faster to install a new part than to repair large damages.
Remove all parts from the damaged area, except those that will help restore the original shape of the damaged body (such as headlight frames, etc.) Cut out damaged or rusted metal.
Use a wire brush to clean the damaged area to remove powdery rust. If the back of the rusted area is accessible, treat it with anti-corrosion paint.
Before you start priming, seal the holes. This can be done by riveting or screwing the sheet metal in place, or by filling the holes with metal mesh.
Once the hole is sealed, it can be primed and painted. (See the next subsection on priming and painting).
Priming and painting
Before reading this Item, see the dents, deep scratches, rust holes and puncture repair items.
There are many types of body primers. A wide nylon brush or flexible plastic will be needed to apply and smooth out the primer. Mix a small amount of primer with thickener in a clean container (use thickener sparingly). Follow the manufacturer's instructions on the package. Using a brush, apply the primer to the prepared surface. To achieve the desired contour and level the surface, draw the brush across the surface of the primer each time. As soon as you achieve contours close to the original, stop applying the paste. Continue applying thin layers of paste every 20 minutes until the filler level is close to the metal around.
Once the filler has set, excess can be removed with a file or sandpaper. Use coarser grit paper first and finish with finer grit paper. Always wrap the sandpaper around a flat block to ensure the surface is completely smooth. Fine sandpaper should be rinsed in water periodically while sanding the surface to ensure a very smooth surface.
When performing such repairs, take care to preserve the body surface. Rinse the repair area with clean water to remove all sandpaper dust.
Spray the primer aerosol onto the surface to be treated. This will allow you to see the defects in the filler surface. Repair the defects with new primer or filler and sand the surface again with sandpaper. Repeat this procedure until you are sure that the surface is perfect. Rinse the area with clean water and let it dry.
Now you can start painting. This is done by spraying in a warm, dry, windless and dust-free place. These conditions can be created in a paint shop, but if you have to work outdoors, choose a dry, windless day. If you work indoors, wet the floor with water to protect against dust. Trim parts such as chrome strips, door handles, etc., should be protected or removed. For this, use masking tape and several layers of newspaper.
Before spraying, shake the paint bottle well. Then apply a test layer and practice the spray painting method. Paint the repaired area. It should be applied to a well-dried thick layer of primer.
Start spraying from the center of the repair area and then, using circular motions, reach the edges. Paint approximately two inches beyond the edge of the repair. Remove all protective coatings 10 to 15 minutes after finishing spraying. Allow the new paint to dry for at least two weeks, then use a special polishing compound to blend the contour of the new paint with the old. Finally, apply a wax coating.
Plastic parts
With the increase in the number of plastic body parts used by car manufacturers, (such as bumpers, spoilers and, in some cases, main body panels), the question of repairing more serious damage to them arose. The basic repair technique involves making grooves along the crack line in the plastic part. The damaged part is then welded using a hot air injector to heat and melt a plastic filler rod into the groove. The excess plastic is then removed and the repaired area is leveled. It is important that the correct filler rod is used, as body parts can be made of different types of plastic, such as polycarbonate, ABS, polypropylene.
Less serious damage (friction, minor cracks, etc) can be repaired with epoxy resin filler. It usually cures within 20-30 minutes and is ready for sanding and painting.
If you are restoring a part entirely with epoxy filler, the problem arises in choosing the right paint to finish the repair that will be compatible with the type of plastic used. At one time, the use of universal paint was not possible due to the complex range of plastics encountered when repairing body parts. Standard paints will not paint plastic or rubber at all. But now it is possible to purchase plastic body parts that come with a primer and paint for surface treatment. First, the damaged part is repaired and dried (up to 30 minutes). Then a primer is applied and dried for an hour before the special paint is applied. The result is a correctly matched color and a paint with the properties of flexible plastic or rubber.