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Automobile PPF manufacturer UPPF will tell you about the so-called deep scratches on the paint surface, that is, scratches that are deep enough to the primer layer or even expose the sheet metal. If such scratches are not treated in time, they will not only have a great impact on the appearance of the car, but more importantly, they will easily corrode the paint surface and shorten the service life of the sheet metal. Therefore, they must be repaired in time.

Deep scratches include traumatic scratches, which are traumas such as partial damage to the car body, deformation of the panel, cracks, etc. due to collisions, scratches, etc., and serious damage to the coating. For deep scratches, the old paint layer on the damaged panel surface should be removed first, and the damaged panel surface of the car body should be repaired by sheet metal or welding methods to meet the requirements of the original shape, size and contour, and then repaired and painted. Its process method is as follows.

(1) Surface treatment.

① Remove the surface coating, rust, and welding slag with a spatula, wire brush, etc., and polish the larger weld joints with a grinding wheel, and then polish with an emery cloth to remove rust and sundries on the bottom surface.

② Clean the scratches with solvent and dry them.

③ Apply a thin layer of primer.

④ Apply a layer of anti-rust paint on the primer film.

(2) Scrape putty.

① Cover the quick-drying putty on the metal layer.

② After the putty is dry, smooth the putty with No. 400 sandpaper.

③ Wipe off the scratches with dewaxing detergent.

(3) Spray the middle coat.

① Cover the unpainted area with special adhesive tape.

② Apply two coats of primer lightly with a spray gun, then a second thicker coat of primer and allow to dry,

③ Sand down the primer with 600 grit sandpaper.

④ If the scratches are still lower than the paint surface, spray another 3~5 layers of primer and repeat the cleaning steps.

⑤ Use 1500~2000# sandpaper to smooth the surrounding part, and then wipe it clean with solvent.

(4) Spray topcoat.

① Spray paint. Select the top coat matching the original car color paint, adjust it according to the original car color, and adjust it to the viscosity that meets the construction requirements, and then spray it after filtering. After each spraying, the leveling time required for the coating film should be allowed, and then spraying again and again. Make the first topcoat coat to a thickness of 30~40um. The paint should have sufficient leveling and drying time after coating, and it usually takes more than 2 hours to dry at room temperature.

② Wet grinding. Use No. 280~320 water abrasive paper to polish the coating film on the basis of spraying four layers of coating film to make it smooth. Blow and wipe with a rag or compressed air. And make the surface dry, it can be heated and dried, or it can be dried naturally. However, it takes a long time to dry naturally, so care should be taken to prevent dust from polluting the surface of the coating.

③ Cover light. In the original topcoat, add less than 20% of varnish, and then properly add thinner and mix it to increase the smoothness. Its viscosity is preferably 15s/25°C. Strain before spraying. The leveling property after spraying is better, so that it is easy to polish and wax the next day. The total thickness is 80~110um.

(5) Polishing and waxing.

① After spraying and drying the body, remove the cover.

②Use No. 400~500 water-grinding paper with water to fully grind the surface of the car body until the surface of the coating film is smooth and flat, and the grinding length is within 100mm back and forth.

③ When polishing with a polishing agent, first wipe the surface of the coating with a rag, and then use a woolen cloth, a sponge, etc. to infiltrate the polishing agent for polishing.

④ After polishing, use glazing wax to polish the gloss to make the surface as bright as new.

If you want to know more about automotive PPF, welcome to consult UPPF, we will sincerely provide you with the most suitable customized solutions for automotive paint.