Automotive repair coating process

The so-called full painting refers to the overall refurbishment of the car paint film, also known as the whole vehicle repair painting. The full painting operation is generally carried out after the car has been used for many years, the body coating is aging (paint film cracking, discoloration, loss of light, etc.), or the car is overhauled; some are also changed to other specified colors according to a certain purpose of use of the user .

According to the degree of aging and damage of the coating, this operation can be divided into full painting after "whitening removal" and full painting after surface layer renovation. Whitening and full coating, when the coating is seriously aging (undercoat cracking, blistering and peeling, rust under the paint film, etc.), use mechanical methods (Grinder plus spatula) or use a stripper to remove the old paint. The coating operation is carried out after the layer is completely removed and the metal surface is exposed. Surface refurbishment painting is carried out when the base coat is intact, only when the top coat layer is aging (discoloration, loss of gloss, chalking, cracking, etc.), and only the damaged top coat layer is removed.

In our country, the whole painting has always been based on "whitening" painting, so the work efficiency is low and the cost is high. With the advancement of automobile technology, the quality of the bottom coating of the car body in many developed countries has approached or reached the level of the same life as the car, and the full painting operation is also developing to focus on the refurbishment of the topcoat layer. The standard full coating process described here is a commonly used method. Obviously, the conditions of each auto body repair shop are different , and the full painting operation is naturally different, but the general steps are similar.

1. Preparation

1. Wash the car, check the coating condition of the repaired car, and formulate the paint repair process and operation guidelines;

2. Removal of components affecting sheet metal and painting operations;

3. Sheet metal repair.

   
   

2. Surface treatment before painting

Removing Old Coating: Peel off old, damaged coating with a paint stripper, sander, or spatula. The peeling surface of the old coating depends on the damage degree of the coating. If the coating of the whole vehicle is cracked, it will be completely peeled off, that is, the car body will be fully painted after "whitening";

1. Grinding the trimmed surface of sheet metal, removing old paint and smoothing;

2. Grinding iron embroidery, grinding the surface after removing the old paint layer with a paint remover;

3. Blow or wipe to remove oil and dust;

4. Moisten the cloth with gasoline or solvent and wipe the treated surface; spray a layer of phosphating primer or paint metal surface treatment agent.

3. Apply the base coat

1. Brush or spray self-drying synthetic resin primer;

2. Dry naturally or force dry under &'(;

3. Apply scraping putty to sheet metal trimming parts and pitted surfaces;

4. Dry naturally or force dry under &'(;

5. Manually smooth the surface of the putty layer by dry sanding or wet sanding;

6. When the four pits cannot be filled with putty once, repeat the putty and grinding procedures until it is filled;

7. A sanding of the painted surface of the entire body;

8. Blow or wipe clean, remove dirt and dust, moisture;

9. Moisten the cloth with solvent or gasoline to remove oil stains;

10. Cover glass windows and the inside of doors with protective covers or paper to prevent paint from adhering during spraying.

    
    

4. Apply intermediate coating

1. Spray a surfacer (or an intermediate coat made of primer and topcoat $-$);

2. Natural drying or forced drying at 60°C;

3. Partial scraping of putty to eliminate putty trachoma, sandpaper pattern, etc.;

4. After the putty layer is dry, use 360 ^​​# ~400 ^# water-resistant sandpaper to wet sand the entire surface;

5. Blow and wipe down the surface.

5. Preparation before topcoat

1. Cover and protect surfaces that do not need to be painted;

2. Moisten the cloth with solvent gasoline, wipe the surface to be coated, and remove oil stains;

3. Prepare paint (color matching, adjust viscosity), and filter.

6. Topcoat

1. Spray topcoat, 2~3 coats of polyester, 3~4 coats of nitro topcoat;

2. Dry naturally or force dry at 60°C .

7. Finishing work

1. Remove the protective cover or paper after the topcoat is dry;

2. Polish with polishing slurry or polishing wax;

3. Install the removed parts and check the coating quality;

4. Cleans the interior and exterior surfaces and tires of the vehicle.