Note: The color insert illustrates the body structure restoration sequence described in detail in the following subsections.
Repair of minor scratches in body structure
If the scratch is superficial and does not penetrate the metal of the body, the repair is very simple. Lightly rub the scratched area with a special compound to remove any loose paint. Rinse the damaged area with clean water.
Apply car paint to the scratch. Continue applying thin layers of paint until the level of paint in the scratch is equal to the level of paint around it. Let the new paint dry for at least two weeks, then polish the surface. After this, cover the scratch area with wax.
If the scratch is deep and the metal of the body begins to rust, then 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 formation. Using a nylon brush, cover the scratched area with filler. If necessary, dilute the filler to create a paste that fills narrow scratches well. Before the filler hardens, rub the surface of the scratch with a thinner filler. This will ensure that the surface being restored is just below the level of the surrounding paint. The scratch can now be painted as described earlier in this Section.
Repairing dents in body structure
When restoring dents, you first need to level the surface as close as possible to the original shape. It makes no sense to try to restore the original shape, since the metal in the damaged area will be deformed and cannot be brought back to its original contours. It is better to make the dent level 3 mm below the metal around it. In cases where the dent is very small, this should not be done at all. If the reverse side of the dent is accessible, it can be straightened easily using a straightening hammer. When doing this job, place a block of wood on the opposite side of the dent to absorb the impact of the hammer and prevent warping the metal.
If the dent is in a section of the body with double layers or is otherwise inaccessible, then use 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 in the metal. The dent can now be straightened out using pliers by pulling on the protruding screw heads.
The next stage of repair is to remove paint from the damaged area and 2.5 cm around. This is done with a wire brush, an emery wheel, or by hand with sandpaper. To ensure the primer adheres well to the body, scratch the area to be treated with a screwdriver or drill small holes in it. Further see point "Primer and painting".
Repairing rusted holes or holes
Remove all paint from the surface to be treated and 2.5 cm around it using a wire brush or sanding wheel clamped in an electric drill. This operation can also be done effectively by hand using 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 major damage.
Remove all parts from the damaged area, except those that will help restore the original shape of the damaged body (type of headlight frames, etc.) Cut out any damaged or rusted metal.
Use a wire brush to clean the damaged area to remove powdered rust. If the back of the rusted area is accessible, treat it with anti-corrosion paint.
Fill any holes before you begin priming. This can be done by riveting or attaching a sheet of metal with screws, or by filling the holes with metal mesh.
Once the hole is sealed, it can be primed and painted. (See next section on priming and painting).
Primer and painting
Before reading this Clause, please see the Clauses on Dents, Deep Scratches, Corroded Holes, and Hole Repair.
There are many types of body primers. A wide nylon brush or flexible plastic will be needed to apply and level the primer. Mix a small amount of primer and thickener in a clean container (use thickener sparingly). Follow the manufacturer's instructions on the packaging. Using a brush, apply primer to the prepared surface. To achieve the desired contour and level the surface, brush the brush across the surface of the primer each time. As soon as you reach contours close to the original, stop applying the paste. Continue applying thin layers of paste every 20 minutes until the level of filler is close to the level of the surrounding metal.
Once the filler has set, excess filler can be removed with a file or sandpaper. Use coarser-grain paper first and finish with finer-grain paper. Always wrap the sandpaper around a flat block to ensure the surface is completely smooth. While sanding the surface, the fine sandpaper should be rinsed periodically in water to obtain a very smooth surface.
When making such repairs, take care to preserve the surface of the body. Rinse the repair area with clean water to remove all sandpaper dust.
Spray an aerosol primer onto the surface to be treated. This will allow you to see defects in the surface of the filler. Repair any defects with new primer or filler and sand the surface again with sandpaper. Repeat this procedure until you are sure the surface is perfect. Rinse the area with clean water and let it dry.
Now you can start painting. It is produced by spraying in a warm, dry, windless and dust-free place. These conditions can be created in a paint shop, but if you must work outdoors, choose a dry, windless day. If you work indoors, wet the floor with water to protect it from dust. Trim parts such as chrome strips, door handles, etc. must be protected or removed. To do this, use duct tape and several layers of newspaper.
Shake the paint bottle well before spraying. Then apply a test coat and practice the spray painting method. Paint the area being renovated. It should be applied to a well-dried thick layer of primer.
Start spraying from the center of the repair area and then work in a circular motion to the edges. Paint approximately two inches beyond the edge of the repair. Remove all protective coverings 10 to 15 minutes after finishing spraying. Let the new paint dry for at least two weeks, then use a polishing compound to blend the contours of the new paint into the old. Finally apply the wax coating.
Plastic parts
With the increasing number of plastic body parts used by car manufacturers (such as bumpers, spoilers and, in some cases, main body panels), the question arose of repairing their more serious damage. 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 the plastic filler rod into the groove. Then the excess plastic is removed and the repaired area is leveled. It is important that the correct filler rod is used, since body parts can be made from various types of plastic, such as polycarbonate, ABS, polypropylene.
Less serious damage (scratches, minor cracks, etc.) can be restored with epoxy resin filler. The filler usually hardens within 20-30 minutes and is ready for stripping and painting.
If you are restoring a part entirely with epoxy resin filler, then the problem arises of choosing the right paint to complete the repair, which 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 stain plastic or rubber at all. But now it is possible to purchase plastic body parts that come with 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 applying a special paint. As a result, the color is chosen correctly and the paint has the properties of flexible plastic or rubber.