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Automobile Coating Film Defect Response Daquan

Jun 10, 2020

1. Water spot

1 Features


On the vehicle level, white ring-shaped water droplets are often formed, and rarely appear on the side of the vehicle. Occasionally, water droplets fall off and the coating film dries to produce streaks. Water spots will also appear on the windows or trim.


2 causes


Water droplets (rainwater, tap water or well water used for car washing) contain calcium and silicon. When the water evaporates, the remaining white precipitate will concentrate around the water droplets.


3 repair method


Washing: Wash the vehicle and remove dirt and dust from the surface of the coating.


Polishing: Use a polishing agent to polish the surface of the coating film to remove water spots remaining on the vehicle after washing the car.


4 Countermeasures


Wash the vehicle in a shady place, and wipe off any water droplets remaining on the vehicle after washing the car. After spraying, park the vehicle indoors until the coating film is completely dry to avoid contact with rain.


2. Pollen spots

1 Features


Pollen spots will form slight wrinkles and white dirt on the surface of the coating film. Although it mostly occurs on the horizontal plane of the vehicle, it will also be formed on the side of the vehicle according to the direction of the wind carrying pollen. When pollen falls on the surface of the coating film and is mixed with water, it will produce a spot-like phenomenon of pollen spots, and individual pollen will also form small spots on the surface of the coating film.


2 causes


When pollen falls on the surface of the coating film and comes into contact with water, it will cause the pollen shell to rupture and cause pectin to flow out. After drying, the pectin will shrink and deform the surface of the coating film.


3 repair method


Washing: Wash the vehicle to remove pollen remaining on the surface of the coating.


Heating: The surface of the coating film is heated (70-80°C, 10 minutes) to release stress to remove defects.


Polishing: Use a polishing agent to polish the surface of the coating film to remove any remaining dirt.


4 Countermeasures


Putting a layer of protective wax can effectively protect the paint surface.


Three, bird shit

1 Features


This type of damage is only due to the contact of bird or insect excreta with the coating film, which will cause paint bumps, cracks and flaking on the surface of the coating film, because the excrement contains different components. Although most of the defects are formed on the horizontal surface of the vehicle, they will also be formed on the vertical surface due to the influence of the wind. Depending on the temperature of the outer panel of the vehicle or the composition of the excreta, cracking occurs about a week after contact.


2 causes


The organic acid in the excrement penetrates into the coating film and causes the coating film to swell. In addition, organic acids will separate the molecular structure of the coating film, plus temperature changes, ultraviolet light and moisture, which will eventually cause the coating film to crack and flake. The extent and shape of the damage on the surface of the coating will vary in accordance with the type of bird or insect or their food.


3 repair method


Heating: The surface of the coating film is heated to evaporate moisture and organic acids that penetrate into the coating film.


Polishing: If there are residual raised parts, grind the raised parts and polish with polishing agent.


Spraying: Use about 1500 grit sandpaper to remove the defective parts, and spray again.


Four, iron powder

1 Features


This type of defect shows small red rust spots on the horizontal surface of the vehicle. It feels rough to the touch and cannot be washed away with water. When the rust remover is applied to the surface of the coating film, the color of the rust spots will change to reddish purple.


2 causes


If the vehicle is parked near a railway or iron factory where iron powder is generated, the iron powder may come into contact with the coating film of the vehicle body and adhere to the coating film, and it may rust and erode the coating film.


3 repair method


Apply rust remover: Use rust remover to remove iron powder on the surface of the film. Rust removers use chemical reactions to convert iron powder into red rust (iron oxide). However, it does not completely remove iron powder.


Use iron-removing powder clay: Use iron-removing powder clay to remove rusty iron powder that has sunk into the coating surface.


Polishing: Polishing removes minor scratches on the coated surface.


Five, flying stone damage

1 Features


When the vehicle is driving, some small stones will hit the coating film and cause the coating film to peel off. This situation often occurs at the front edge of the vehicle hood or roof. If the small stone bullet jumps up, it may also damage the door sill plate, the door lower wall or the outer part of the wheel arc, and the part where the coating film peels off usually forms a sharp or jagged surface. Occasionally, small stones can cause small depressions in the middle of the area.


2 causes


When the vehicle is running, small stones hit the coating film surface, as a result, the coating film peels off.


3 repair method


Grinding: Grind the defective parts until the surface is smooth. If there is rust, the rust needs to be completely removed.


Spraying: Use color-adjusted paint to re-spray the area.


4 Countermeasures


A simple method is to perform local repair on the damaged area, and then remove and polish the protruding parts.


6. Fading or whitening

1 Features


After the vehicle is used for a long time, the coating film will lose its gloss. (Fade) The light-colored paint will turn yellowish. The surface of the coating film will become white, powdered and dull.


2 causes


This defect is caused by the deterioration of the resin and pigment in the coating film due to ultraviolet rays, high temperature and moisture.


The discoloration is caused by the deterioration of the pigment, the yellowing is caused by the deterioration of the resin by ultraviolet irradiation, and the whitening and pulverization are caused by the deterioration of the resin to become powdery.


3 repair method


Polishing: Use the polishing operation to remove the defective layer.


Spraying: If polishing still fails to repair the defect or reoccurs after repairing and remedying, remove the defect layer and spray the area again.


4 Countermeasures


Park the vehicle wherever possible. When repainting, use two-component urethane paint instead of nitro paint.


7. Particulate matter

1 Features


When foreign particles sink into the coating film, the surface of the coating film will form a convex shape. This type of defect will form many different convex shapes according to the type and shape of foreign particles.


2 causes


In the coating process, dust or particles around the work area adhere to the coating film, and such defects will occur after remaining on the coating film and hardening. It is also possible that foreign particles have already been mixed with the paint to cause such defects.


3 repair method


Grinding: Use grinding stone or No. 2000 sandpaper to grind off the material.


Polishing: polishing with polishing agent to remove sandpaper marks.


Spraying: If different colors appear after grinding, use appropriate sandpaper (about 400 grit sandpaper) to grind the area, and then spray the area again.


4 Countermeasures


Keep the painting work area tidy at all times and clean the paint room thoroughly before moving the vehicle into the paint room. Sprayers must wear dust-free clothing, and the filter in the paint room must be replaced regularly.


Eight, vertical flow

1 Features


Before the coating film dries, the paint flows and gathers.


2 causes


Apply too much paint thinner when the coating film is thick. Using slow-drying thinner may also cause sag.


3 repair method


Grinding: Use a grindstone or No. 2000 sandpaper to grind the defects until smooth.


Polishing: polishing with a polishing agent to remove sandpaper marks.


Spraying: If the vertical flow area is too large or contains air bubbles, grind the defective part smoothly and then spray the area again.


4 Countermeasures


Use spray gun under appropriate spraying conditions.


When diluting the paint, the appropriate situation and the appropriate amount of thinner should be used.


The film thickness should not be too thick when spraying, it should be sprayed multiple times until it reaches the standard film thickness.


9. Fisheye

1 Features


This type of defect will form a crater-like depression on the coating surface.


2 causes


Before spraying, the surface has not been properly cleaned, and there are oil stains or silicon remaining on the surface of the coating film.


If oil stains (or silicon) remain on the surface of the object to be coated, the paint will not adhere to the surface to be coated, resulting in fish eyes.


3 repair method


Grinding: Grind the defective part until the surface is smooth.


Spraying: Use color-adjusted paint to re-spray the area.


4 Countermeasures


Thoroughly clean and degrease the surface of the object before spraying. After degreasing, do not touch the surface of the coating film with your hands. Do not perform polishing operations in the painting work area.


10. Uneven silver powder

1 Features


When the reflective pigment (aluminum or pearl mica pigment) in the silver powder paint or pearl paint floats, uneven silver powder reflow will occur.


2 causes


In the coating process, if the uneven arrangement of the reflective pigments in the coating film is not coordinated, the operation of the spray gun results in uneven film thickness. If the coating film takes a long time to harden, add too much thinner or use the slow-drying type. The thinner coating film has static electricity on the surface.


3 repair method


Slightly increase the distance of the spray gun to eliminate uneven silver powder. Allow enough time for the coating to dry before spraying varnish. According to the instructions of the paint manufacturer, give the coating film a prescribed drying time. Use the appropriate number of sandpaper (about 1500 sandpaper) to grind the surface. Repaint the area.


4 Countermeasures


Maintain stable spray gun operation skills and spraying conditions.


Use antistatic degreasing agent.


Use appropriate thinner and amount to dilute the paint.


11. Orange peel

1 Features


This type of defect is the phenomenon of orange peel on the surface of the coating film. However, the orange peeling pattern of the anti-sandstone coating used under the door panel and the door sill is not a defect of the coating.


2 causes


When the coating film has hardened before leveling;


When the viscosity of the paint is too high, use a paint thinner with an inappropriate evaporation rate;


Excessive air pressure or the distance of the spray gun is too far;


The surface temperature of the object to be coated is high.


3 repair method


Grinding: Use No. 2000 sandpaper to grind the coating film for directions until the surface is smooth.


Polishing: Use the polishing operation to adjust the texture. If the grinding operation has been carried out before, the sandpaper marks must be removed.


Spraying: Use the appropriate number of sandpaper (about 1500 sandpaper) to grind the part to be ground, and then use the color-adjusted paint to re-spray the part.


12. Solvent bubbles

1 Features


Such defects will form small holes or generate a group of bubbles on the surface of the coating film. The solvent bubbles often occur on the horizontal surface or the thicker part of the coating film on the edge of the steel plate. If the coating film is forced to dry immediately after spraying, the surface of the coating film will be hardened before it is dried. When the internal solvent is to develop, it will accumulate on the surface of the hardened coating film and cause bulging. Moreover, small holes are formed when the solvent penetrates the surface of the coating film.


2 repair method


Grinding: Grind the defective part until the surface is smooth.


Spraying: Use color-adjusted paint to re-spray the area.


3 Countermeasures


According to the instructions of the paint manufacturer and the temperature of the paint to be used, select the appropriate thinner, adjust the viscosity of the paint, and allow sufficient time to stand. Allow the primer to dry thoroughly.


13. Pinhole

1 Features


If there are already small holes on the surface of the coating film, and the outer coating film cannot fill it up, there will be pits on the surface of the coating film.


2 causes


Pinholes appear in midcoat primer or putty.


3 repair method


Grinding: Use No. 2000 sandpaper to smooth the defect.


Polishing: Use polishing to remove defects/sandpaper marks.


Spraying: Use an appropriate number of sandpaper (about 1500 sandpaper) to grind the part, and then use the adjusted paint to re-spray the part. A simple method is to apply local spraying on the concave parts, remove the convex parts, and polish the surface.


4 Countermeasures


When applying putty, apply force to prevent air from mixing into the putty;


After spraying the intermediate coating, fill the pinhole with nitro putty if necessary.


14. Sandpaper marks

1 Features


The sandpaper used to grind the undercoat layer can not be filled with the coating film. According to the way the sandpaper moves or the pneumatic grinding tool used, there are straight, curved, and spiral sandpaper marks.


2 causes


The sandpaper marks used to grind the undercoat layer cannot be filled by the coating film: if the undercoat layer is not completely dried, it will be ground and then sprayed with topcoat; spray a thick coating film with high viscosity or use a slow-drying type Paint thinner.


3 repair method


Grinding: Use No. 2000 sandpaper to remove sandpaper marks.


Polishing: Use sandpaper marks for polishing to remove.


Spraying: Use an appropriate number of sandpaper (about 1500 sandpaper) to grind the part, and then use the adjusted paint to re-spray the part.


4 Countermeasures


Use the appropriate number of sandpaper for each process.


Allow enough time for the primer to dry.


Select the appropriate form of thinner, adjust the viscosity of the paint according to the instructions of the paint manufacturer, and spray in several times.


Fifteen, atomic gray marks

1 Features


After the topcoat is sprayed, there are traces of repaired by putty. If the different uplift ratios between the old coating and the putty are due to the penetration of the solvent, the shrinkage will occur along the plume, which is how the putty marks are produced.


2 causes


Putty drying is insufficient. The old coating film is in the form of nitro, or a thick intermediate coat or top coat sprayed at one time, will cause the occurrence of polyester putty marks.


3 repair method


Grinding: Use No. 2000 sandpaper to smooth the defect.


Polishing: Use the texture of the polished net defect to adjust the smoothness.


Spray Use appropriate number of sandpaper (about 1500 sandpaper) to grind the part, and then use the adjusted paint to re-spray the part.


4 Countermeasures


Put a proper amount of curing agent in the putty and give it a thorough drying.


Select the appropriate form of diluent and mix in the specified amount.


16. Polishing marks

1 Features


On light-colored surfaces, such defects will appear as black markings. If you want strong sunlight to shine on the dark surface, there will be white mist like aurora on the surface.


2 causes


Light color series: Dirt (or water spots) will accumulate in the fine scratches caused by polishing and cause black spots.


Dark color: The fine scratches caused by polishing will reflect irregular light and form a white matte surface like aurora. If the coating film is not completely dried, fine scratches may occur after polishing.


3 repair method


Dry before polishing, and carefully polish the surface.


4 Countermeasures


In the final polishing operation, use a very fine polishing agent: give the coating film a specified drying time before performing the polishing operation; use a clean polishing pad.


17. Bubbling

1 Features


Foaming is the formation of spherical ridges on the surface of the coating film; usually the blister with a diameter of 0.5-2.0mm will converge in a small area, and the bulge will increase with time.


2 causes


Moisture exists in the bottom layer of the coating film, and the coating film is pushed up. The coating is sprayed on a base coat that has not been cleaned of oil stains or moisture.


Moisture penetrates into the coating film and collects around the dirt. If the external temperature rises, the moisture under the coating film will evaporate, and the upward pressure will cause the coating film to swell and blister.


Usually empty-handed or improper cleaning will leave fingerprints or wipe marks on the surface of the coating film, causing blistering.


If the primer layer is made of a material with low water resistance or poor adhesion, blistering will occur throughout the spray area. -Generally speaking, when the vehicle is sprayed under high temperature and high humidity, blistering is more likely to occur.


3 repair method


Grinding: Grind the old coating film to the steel plate.


Spraying: Start from the primer operation and spray again.


4 Countermeasures


Do not touch the surface of the coated object when empty-handed. Do not use paints with low water resistance and poor adhesion;


Before spraying, thoroughly clean and degrease.


Source:www.up-resin.com

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