For publication of more detailed information about body repair work, please contact the special "car body repair manual".
Repair of minor body scratches
If the scratch is superficial and does not reach the metal of the panel, the repair procedure is very simple. Lightly rub the damaged area with paint restorer or very fine lapping paste to remove loose paint particles and remove the protective wax layer from the surrounding surface. Rinse the treated surface with clean water.
With a thin brush, apply a layer of exterior car paint to the scratch; Apply paint in thin layers until the surface of the paint inside the scratch is flush with the layer of undamaged paint surrounding the scratch. Allow the fresh paint to cure for at least two weeks, then mask the transition from the newly painted surface to the old paint as much as possible by rubbing it with paint restorer or very thin lapping paste. Finally, apply a protective wax coat.
If the scratch has reached the metal of the body, which may cause corrosion of its metal, the restoration procedure will be different from the above. Remove loose rust particles from the bottom of the scratch with a penknife, then coat the scratch with a rust inhibitor to prevent further corrosion. Using a nylon or rubber applicator, fill the scratch cavity with putty paste. If necessary, to thin the paste when filling narrow scratches, mix it with cellulose thinner. Before the paste hardens, soak a finger wrapped in a soft cotton cloth in cellulose thinner and quickly smooth the putty surface of the scratch; this will provide a slight concavity of the machined surface. Now the scratch can be painted over, as described earlier in this Section.
Repair of deformed surfaces
Deep dents are first of all stretched to give them a shape as close as possible to the original. Full restoration of the form is impossible, because. the metal of the damaged panel is stretched under the impact load. It is optimal to make the deformed surface level approximately 3 mm below the level of the surrounding undeformed body part. In the case of a very shallow dent, it makes no sense at all to try to pull the panel out. If there is access to the inside of the deformed area, restoration of the shape can be carried out by tapping the dent with a hammer with a wooden or plastic head. When tapping, to dampen hammer blows and thereby prevent bending of a larger than required section of the panel, firmly press a wooden block of a suitable size to the damaged area from the outside, which will absorb hammer blows, etc. prevent the appearance «belly» over large areas of the body.
In the event that there is deformity in the area of the body having a double structure, or if access to the wrong side of the dent is otherwise unavailable, a different pulling technique should be used. Drill inside the deformed area, especially in the deepest part of it, a series of small holes. Then screw long self-tapping screws into the holes so that they are securely fixed in the metal. Now the shape of the panel can be restored by pulling out the dent, grabbing the protruding heads of the self-tapping screws with pliers.
The next step is to remove the paint from the damaged area and 2.5 cm around it. This procedure is most easily performed using a wire or abrasive nozzle mounted in an electric drill chuck, although it can be done by hand with sandpaper just as effectively. The final procedure to prepare for puttying is to scratch the bare metal surface with a screwdriver or file shank, or alternatively, drill a series of small holes into the damaged area. This will ensure the best engagement of the putty with the metal.
To complete the repair, refer to the Section on Filling and Painting.
Restoration of holes formed as a result of corrosion and holes
Remove all paint from the damaged area and 2.5 cm around it, either by hand or using the attachments of an electric drill. After that, the degree of damage or corrosion can be determined and decide whether it makes sense to repair or it is more reasonable to replace the entire panel (if possible). New panels are not as expensive as many people think, and it's often faster and more efficient to replace a panel than to rebuild huge corroded sections of a body.
Remove all trim parts from the damaged panel, except for those that can serve as templates for restoring the original shape of the panel (such as headlight housings, etc.). Then, using sheet metal shears or a hacksaw blade, remove any badly corroded and loose pieces of metal from the panel. To create a slight indentation necessary for puttying, bend the edges of the hole inward.
Remove powdered rust from the surface of the remaining metal. Treat the affected area with a rust inhibitor; also process the wrong side, if you have access to it.
Before you start puttying, you need to somehow block the hole. This can be done with aluminum or plastic mesh or aluminum tape. For blocking large openings, it is best to use aluminum or plastic mesh, or a fiberglass mat. Cut a piece of mesh of approximately the right size and shape, then lay it over the hole so that its edges are below the level of the surrounding undamaged surface of the body panel. The mesh can be fixed in place with a few wads of putty around its perimeter.
Aluminum tape is used to seal small or very narrow openings. Unwind a piece of tape of the desired length from the reel, give it approximately the required shape with scissors, then remove the paper sticker protecting the sticky layer (if any), and stick the tape over the hole, blocking it. If the width of one piece of tape is not enough, you can apply several pieces with overlap. Carefully smooth the edges of the tape with the handle of a screwdriver, ensuring it adheres securely to the wrong side of the metal surrounding the hole.
Body repair - puttying and painting
Before proceeding with the procedures of this Subsection, read the information of the previous ones.
Many different types of putties are available, but for this type of work, proprietary sets consisting of a tin of putty and a tube of hardener are best suited. Use a wide, flexible plastic or nylon applicator to ensure that the paste is applied smoothly and in the desired contour.
On a clean piece of cardboard or plywood, mix a small amount of putty. Carefully dose the ingredients, following the manufacturer's instructions on the package, because. adding the wrong amount of hardener can cause the mix to cure too quickly or too slowly. Using the applicator, apply the prepared putty to the surface prepared for puttying; to give the surface the desired level and contour, run the applicator across it. Upon reaching the contour of the treated surface close to the original, stop applying the putty, because. with excessive enthusiasm, it can become "sticky" and start sticking to the applicator. Continue to apply thin coats of putty at 20 minute intervals until the putty surface begins to protrude slightly from the undamaged area of the panel.
After hardening, excess putty can be removed with a metal bar or file. Next, the puttied surface should be treated with waterproof sandpaper of gradually thinning grades, starting with No. 40 and ending with No. 400. Always wrap the paper around a flat piece of rubber, cork, or wood to keep the work surface perfectly flat. Moisten the waterproof paper with water constantly during processing. This will ensure absolute smoothness of the surface at the final stage of grinding.
After completing this stage of work, the surface to be treated should be surrounded by a ring of bare metal, which, in turn, should be surrounded by a nulled edge of good paint. Rinse the treated surface with clean water, removing all sanding dust from it.
Spray a light primer over the entire surface of the treatment with a thin layer - this will help to visually identify all processing defects. Eliminate all the mistakes made by smearing them with fresh putty, and again treat the surface with sandpaper. Repeat this procedure until you reach the result that satisfies you. Rinse the finished surface with clean water and allow it to dry completely.
The surface is now ready for painting. Aerosol handling should be carried out in a warm, dry, windless and dust-free atmosphere. These conditions are easiest to meet when working indoors, but if you must work outdoors, you must carefully choose the day of painting. When working indoors, dampen the work area with water to tamp down airborne dust. If a separate body panel is being painted, cover the surrounding panels; this will help to minimize the effect of a slight difference in tones between the old and new paint. You should also cover the trim parts of the body (chrome lining, door handles, etc.). Use duct tape and several layers of newspaper to cover.
Shake the spray can thoroughly before painting, then test it on a test surface to achieve the desired level of skill. Cover the treated surface with a thick coat of primer, achieving thickness by applying several thin coats rather than one thick coat. Use #400 waterproof sandpaper to smooth the surface. Moisten the surface and waterproof paper periodically with water during processing. Finally, rinse the surface again with clean water and allow it to dry completely before applying the paint.
Apply a top coat of paint, again gaining thickness by applying several thin coats in succession. Start painting from the center of the surface to be restored and move in circular motions to the periphery until the entire surface is painted and about 5 cm of the surrounding old paint is painted. 10-15 minutes after applying the last coat of paint, remove the covering material from adjacent panels and trim elements.
Let the paint dry for at least two weeks, then use a paint restorer or very thin lapping paste to mask the transition from the newly painted surface to the old paint as much as possible. Finally, apply a protective wax coat.
Plastic components
Due to the fact that car manufacturers are increasingly using plastic body parts (such as bumpers, spoilers and in some cases even large body panels), the correction of more serious damage to these elements comes down either to placing it on specialists in this field, or to a complete replacement of the elements themselves. Repair of such damage by the owner of the car is practically impossible due to the significant cost of equipment and materials necessary for its implementation. The repair technology is based on making grooves in plastic along the crack line using a grinding nozzle on an electric drill. After that, the cracked part is welded using a hot air gun that melts a rod of plastic filler inserted into the groove. The excess plastic is then removed and the surface is sanded to a smooth finish. It is important that the plastic filler rod is chosen correctly, because body components can be made from different grades of plastic (polycarbonate, ABS, polypropylene, etc.)
Less serious damage (scuffs, abrasions, minor cracks, etc.) can be eliminated by the owner of the car using a two-component epoxy putty. Mixed in equal proportions, it is applied in the same way as putty for metal surfaces. It usually rises in 20 to 30 minutes, ready for sanding and painting.
If the owner completely replaces the element himself, or restores it with epoxy putty, he is faced with the problem of finding the right paint that is compatible with the grade of plastic from which the part is made. At one time, the use of universal paint for plastic components was not possible due to the variety of grades of plastic used. Standard paints generally do not adhere well to plastic or rubber surfaces. Now, however, there are plastic body finish kits that include a pretreatment primer, a secondary primer, and a decorative top coat. Kits are usually accompanied by comprehensive instructions, but in general terms, the technology is that a preliminary primer is first applied, which must dry for at least 30 minutes. Then a secondary primer is applied, and after it dries within an hour, a layer of specially matched exterior paint is applied. The result is a properly painted component where the paint is malleable enough to bend with plastic or rubber, which is not the case with standard paint.