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How to remove spots on the body

05-19

The spot repair coating should pay more attention to the same gloss than the whole board repair coating, and the freshness of the surface is almost the same. It is almost completely integrated with the surroundings, and the naked eye can almost be indistinguishable. The surrounding area is gradually and gradually over.

车身上的斑点怎么清除 车身斑点修补喷漆介绍 车身斑点清除 汽车钣金喷漆 第1张

(1) Surface treatment before patch repair

1) Wash the body with neutral detergent and water.


2) Wash the body with solvent.


3) Grind oblique mouth (commonly known as thin edge).


If the new paint layer directly covers the damaged part of the old paint surface, the shape of the damaged paint film can be exposed through the new paint layer. Therefore, the edges of the damaged part must be sanded to a gradually thinning smooth transition state. When the damage degree of the repair paint film is not deep enough to the metal substrate, the thin edges here are required to be finer and smoother, creating conditions for repair without traces.

打磨块或其他体积较大的打磨块垫包砂纸进行打磨,打磨的方法采用划圆圈砂的方法。 If you use a grinding block to grind the oblique opening, the steps are as follows: When the diameter of the repair area is between 15 and 20 cm (smaller area), it is recommended to use a rubber sanding block or other larger grinding block to cover the sand with sandpaper. Methods The method of circle sand was adopted. For large area sanding, it is straight sand. When manual sanding is used, the outer edge of the damaged part is firstly ground with 80 grit sandpaper, then 240 grit sandpaper, and then 360 or 400 grit sandpaper. During the sanding process, always use a sponge dipped in water to keep the surface moist and remove the marks left by the sandpaper.
If you use a sander to grind the bevel, it is recommended to use a track-type or double-acting sander equipped with a flexible pad. 边缘。 Sand the rough lacquered edges with an outer edge that is approximately 2.5 cm wide. The angle between the grinder and the surface to be ground must not be greater than 10 °, otherwise grooves will be ground on the painted surface.
After the rough paint surface is smoothed, put the grinding disc flat and move the grinding machine back and forth to grind the oblique mouth. Sand the entire damaged area from the inside out. During construction, you should often stop and touch with your hands to see if there are rough edges. New edges must be ground on the entire outer edge, and all previously damaged edges must be ground off to avoid peeling when repainting. After the surface is smooth, the work of grinding the bevel is not completed when the end bands of the topcoat and the primer appear.

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4) After removing the rust on the bare metal substrate in the center of the spot, use a two-component metal surface conditioner for treatment according to the requirements of the product manual. 剂的表面及其周围区域。 Moisten a cloth with water at a later time to wipe the surface and surrounding area coated with the metal surface conditioner . Repeat several times until it is clean.

5) The exposed metal surface should be covered with a primer that matches the original primer. Avoid cross-linked primers between the volatile coatings, then spray 3-4 layers of intermediate paint, spray new The paint should be slightly higher than the original topcoat (the intermediate coating generally shrinks by 50%). After drying for 30 minutes, sand it with 400 grit sandpaper.
For the processing of the intermediate coating and the adjacent original topcoat, use 400-gauge sandpaper dipped in water to polish the center of the intermediate coating. The middle coating must be applied to the original topcoat smoothly. The manual polishing method is used to remove the overspray on the adjacent original topcoat, and the edges of the intermediate coating are wiped and polished to polish the entire polished area on the same paint. Wipe the polished surface with a cloth dampened with a small amount of water and clear solvent.
When patching modified acrylic topcoats, pay special attention to sanding the intermediate coating first with 400-grit sandpaper to sand the oversprayed edges around the spots. When grinding, pay attention to using a suitable grinding module dipped in water to polish, and do not polish the center of the spot when starting to polish. When sanding the center of the spot, pay attention to the progress of the sanding and never overdo it. Once you find that the rough sanding marks in the center of the spot have been smoothed, stop grinding immediately. Pay attention to how the intermediate coating smoothly extends to the original topcoat during the sanding process. 溶剂的抹布将打磨好的表面擦拭干净。 Finally, wipe the polished surface again with a cloth dampened with water and a little cleaning solvent.

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(2) Construction of top coat during patch repair

1) Spraying of plain paint.

The types of topcoats used for spot repair and whole board repair are the same, but the coating process is different. In the spraying of plain paint, the construction process of thermoplastic acrylic topcoat is mainly introduced as an example.

① Preparation before spraying.

First of all, check the type of paint, color number, type of thinner, and the integrity of equipment such as spray gun. Prepare the two spray guns after confirming that the paint has been stirred evenly. Mark "color paint" on the spray cup of the first spray gun and put in the finished top coat. Temporarily set the spray gun to the middle position, and spray the sample, and record its spraying level, interval time, dilution ratio, spray gun pressure, etc., so that the color of the obtained topcoat is consistent with the original topcoat. In order to compare with the original rolling color of the car, spray the template in a full-cover manner until the color matching result is satisfactory. In the second spray gun, add a mixture of 1 part slow diluent, 1 part medium diluent, and 5% by volume of thermoplastic acrylic varnish. Mark the "anti-fog paint" on the spray cup. spare.

② Spray coating construction.

First spray the first coat of paint on the surface of the intermediate coating with the first spray gun, and use the edge construction method at the beginning and end of each shot. Then spray the anti-fog paint on the edge of the spot with a second spray gun. After a few minutes, spray the second and third layers in the same way. Each layer should be larger than the previous layer until it reaches the full range. Cover. After spraying, it was dried at normal temperature for 1 h, and then sprayed with 3 layers of thermoplastic acrylic varnish. The varnish used here was diluted with a slow thinner to a volume fraction of 200%, and finally the edges of the acrylic varnish were sprayed with an antifog spray. After 1 day of drying (preferably 1 week), the polishing operation can be performed. Because the thermoplastic acrylic paint shrinks about 50% after spraying. Therefore, a certain amount of system must be reserved during construction.

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