Contents: Repair of small scratches ↧ Dent repair ↧ Repairing rust holes or cracks ↧ Filling and painting ↧
Repair of small scratches
1. If the scratch is superficial and does not affect the body metal, the repair is very simple. Lightly rub the scratched surface with a fine polishing compound to remove loose paint and wax. Rinse the surface with clean water.
2. Apply touch-up paint to the scratch using a small brush. Continue applying thin coats of paint until the scratch is completely filled. Allow the new paint to dry for at least two weeks, then blend it with the surrounding paint by buffing the painted area with a fine polish. Finally, apply a top coat of wax to the scratched area.
3. If the scratch has penetrated the paint and damaged the metal body, causing rust, a different repair procedure is necessary. Remove the rust from the base of the scratch with a pocket knife, then apply rust-preventing paint to prevent future rust. Using a rubber or nylon applicator, coat the scratched area with glaze (glaze is a translucent layer of paint). Before the glaze in the scratch hardens, place a piece of smooth cotton cloth around the tip of your finger. Dip the cloth in thinner, then quickly run it around the surface of the scratch. This will help you ensure that the surface of the glaze is slightly sunken. You can now paint the scratch as described earlier in this section.
Note: If necessary, the glaze can be mixed with thinner to make a very thin putty, which is ideal for filling narrow scratches.
Dent repair
4. When performing dent repair, the first thing to do is to straighten the dent so that the damaged area is as close to the original shape as possible. There is no point in trying to completely restore the original shape, since the metal in the damaged area is stretched and cannot be restored to the original contour. It is better to level the dent so that its level is approximately 3 mm below the level of the surrounding metal.
5. If the dent is very small, there is no point in leveling it at all.
Caution: Hold a wooden block firmly against the back of the metal to absorb the hammer blows and prevent stretching of the metal.
6. If the dent is in a part of the body that has a double layer, or something else makes it impossible to access from the inside, a different procedure must be used. Drill several small holes in the metal inside the damaged surface, preferably in the deepest parts. Screw long, self-tapping screws into the holes so that they engage firmly with the metal. Now you can straighten the dent by pulling on the protruding heads of the screws with pliers.
7. The next step in the repair is to remove about an inch of paint from the damaged area and the surrounding metal. This can be done with a wire brush or a sanding disc on a drill, but can be done just as effectively by hand with sandpaper. To complete the preparation for filler, use a screwdriver or file to smooth the exposed metal, or drill small holes into the damaged area. This will ensure good adhesion between the metal and the glaze. To complete the repair, see the Filling and Painting subsection later in this chapter.
Repairing rust holes or cracks
8. Remove all paint from the damaged area and the surrounding metal within a radius of approximately 2.5 cm using sandpaper or a wire brush attached to a drill. If these are not available, this job can be done by hand using several sheets of sandpaper.
9. Once the paint is removed, you can determine the extent of the corrosion and decide whether to replace the entire panel or, if possible, repair the damaged area. New body panels are not as expensive as many people think, and it is often much faster to install a new panel than to repair a large area damaged by rust.
10. Remove all trim pieces from the damaged area, except for those that act as a guide to the original shape of the damaged car body, such as the headlight housing, etc. Using metal shears or a hacksaw blade, remove all damaged metal, as well as any other metal that shows signs of rust. Use a hammer to bend the edges of the hole inward to create a small recess for the filler material.
11. Use a wire brush to scrub the damaged area to remove powdery rust from the metal surface. If the back of the rusty surface is accessible, coat it with anti-corrosion paint.
12. Before final sealing, plug the hole in some way. This can be done with sheet metal riveted or screwed into the hole, or wire mesh can be installed in the hole.
13. Once the hole is plugged, the damaged area can be filled and painted. See the next subsection on filling and painting.
Filling and painting
14. There are many body repair fillers available today, but honestly, a body repair kit that contains a filler paste and a tube of polymer hardener is best for repair work. You will need a wide flexible plastic or nylon applicator to smooth out the surface of the filler. Mix a small amount of filler mixture on a clean piece of wood or cardboard (using hardener sparingly). Follow the manufacturer's instructions on the package or the filler will not cure properly.
15. Using the applicator, apply the filler paste to the prepared surface. Run the applicator over the surface of the filler to achieve the desired contour and level the surface of the filler. When the original level and contour are achieved, stop working with the paste. If you continue, the paste will stick to the applicator. Continue applying thin layers of paste at 20-minute intervals until the filler level exactly matches the level of the surrounding metal.
16. When the filler has hardened, you can remove the excess with a file. Next, use sandpaper, gradually increasing its grain size, starting with 180 grit paper and ending with 600 grit waterproof paper. Always wrap the sandpaper around a rubber or wooden block, otherwise the filler surface will not be completely flat. When sanding the filler surface, periodically wet the 600 grit waterproof sandpaper with water. This will help achieve a very smooth surface.
17. The repair area should now be surrounded by a ring of bare metal, which in turn should be surrounded by good, undamaged paint. Rinse the repair area with water until all the dust remaining from sanding has been removed.
18. Apply a thin coat of primer to the entire sanded surface. This will help reveal any defects on the filler surface. Correct any defects with fresh filler or glaze and sand the surface again. Repeat the primer and filler application until you are satisfied with the quality of the filler surface and paint edge. Rinse the surface with clean water and allow it to dry completely.
19. The repair area is now ready for painting. Spray painting should be done in warm, dry, windless weather with no dust in the air. These conditions can be achieved if you have access to a large workshop. However, if you are going to be working outdoors, you must choose your painting day very carefully. If you are working indoors, spray the floor with water. This will help to knock down dust that might otherwise become airborne. If the repair area is on one body panel, cover all surrounding panels. This will help to minimize minor mismatches in paint color. Decorative trim pieces such as chrome trim, door handles, etc. should also be masked or removed. Use masking tape and several layers of paper to mask them off.
20. Shake the paint thoroughly before spraying, then practice spraying it to learn how to do it correctly. Apply a thick coat of primer to the surface to be repaired. It is better to apply several thin coats than one thick one. Using 600 grit sandpaper, sand the surface of the primer until it becomes very smooth. During this operation, the surface to be treated should be thoroughly wetted with water. The sandpaper should also be periodically dipped in water. Allow the primer to dry before applying additional coats.
21. Spray paint on the top coat, building up the thickness by applying several coats. Start spraying from the center of the repair area, then using circular motions, spray the entire repair area and about 5 cm of surrounding paint. Remove all masking material 10-15 minutes after applying the last coat of paint. Allow the new paint to dry for at least two weeks, then use a very fine sanding compound to blend the new paint into the original paint. Finish with a coat of wax.