Corrosion under the layer of old paint or a deep scratch reaching the metal, require immediate intervention, since ignoring these defects will lead to through rotting of the body element. Properly carried out stages of painting car parts allow you to fully restore the geometry and protective properties of the coating, returning the car to its presentation without the need to replace expensive components. Breaking the technology at any of the steps, whether degreasing or drying, is guaranteed to lead to peeling of the material or the appearance of shaking in the future.
The paint refining process (LAC) is a complex chain of physicochemical reactions, where each layer performs a strictly defined function. adhesion The materials depend on the purity of the surface, and the durability of the result depends on the observance of time intervals between operations. Modern materials, such as two-component epoxy soils and acrylic varnishes with UV filters, require precise compliance with mixing proportions and temperature regimes.
Before starting work, you need to make sure that you have the necessary equipment: a spray gun with a properly selected duse, a compressor with a receiver and, preferably, a paint chamber or a well-ventilated room. Krascopults HVLP (High Volume Low Pressure) systems are considered the standard for garage use, providing high material transport and minimal fog. The lack of a professional tool is often compensated by an increase in the number of layers, which thickens the coating and can lead to it cracking when heated.
Dismantling of the element and initial damage assessment
Start with the complete dismantling of the damaged part or adjacent elements, if local painting is impossible without touching the neighboring areas. Removal of the bumper, door or wing allows you to process the ends and internal edges, where most often corrosion foci are born, imperceptible during a superficial inspection. Dismantling It also eliminates the risk of paint getting on seals, glass and plastic linings, which are extremely difficult to wash after drying.
After removing the part, defects are made: the master determines the depth of damage, the presence of dents and the condition of the old paint coating. If rust has already manifested itself through holes or bubbles under the paint, you will need a cut of rotten metal and the installation of repair patches. In cases where the old layer is held firmly and does not have bloating, it is allowed to partially preserve it after careful grinding.
⚠️ Warning: When working with older cars produced before the 2000s, there is a high probability of detecting hidden corrosion under the layers of the factory soil. Always clean the surface to a metal 2-3 cm around visible damage to assess the real scale of the problem.
It is important to prepare the workplace, protecting surrounding objects from dust and abrasive. Use of the grinder with a vacuum cleaner will significantly speed up the process and improve the visibility of the treated area. For hard-to-reach places, such as arches or complex profiles, special nozzles are used or work manually with bars.
Mechanical cleaning and corrosion removal
The main task of this stage is to completely remove iron oxides and create risk on the metal for better coupling with the soil. Cleaning is made to the "white" metal, when there is no rust point on the surface. The use of chemical rust converters is allowed only in hard-to-reach places where machining is not possible, but ideally complete mechanical removal is required.
For primary rough stripping, abrasives with graininess P60-P80 are used, which quickly remove the old material and align the plane. It is impossible to switch to a smaller grain at once, since this can “salt” the surface, clogging the pores of the metal with grinding products. Abrasive materials must be of high quality to exclude the formation of deep scratches that will protrude through new layers of paint.
- 🛠️ Use an angle grinder with a petal disc to remove large volumes of rust.
- 🔍 Visually control the surface at different lighting angles to avoid missing micro foci of corrosion.
- 💨 Blow cleaned areas with compressed air to remove metal dust from the pores.
After rough stripping, the surface is treated with abrasive P180-P240, creating a uniform risk. This is necessary so that the subsequent layers of putty and soil lay flat and did not subside over time. Critically important do not overheat the metal during cleaning, as local heating can cause deformation of thin body iron.
Reconstruction of geometry with putty
If there are dents or irregularities on the parts, they are eliminated with the help of car putty. The material is filled with depressions, trying to apply a layer with a small margin, since shrinkage occurs when drying. For deep damage, a putty with fiberglass, which has high strength, is used, and for the final alignment, soft finishing compositions are used.
The polymerization time of the putty depends on the ambient temperature and the amount of hardener added. Exceeding the norm of the hardener can lead to "boiling" of the mixture and the appearance of pores, and the disadvantage is that the material will remain sticky inside. Polyester putty apply in thin layers, carefully mixing the components to a uniform color without stripes.
Grinding of the putty begins after its complete cooling and hardening. Use a developing powder or aerosol that is applied to the surface before grinding to see high and low points. Grinding is carried out diagonally, so as not to create longitudinal grooves that will be noticeable after painting.
Types of putty
Aluminum putty is easier to process and less heated when grinding, but more expensive than classic. Carbon fiber putty has maximum strength, but requires careful finishing due to its rigid structure.
Finish grinding is performed with the abrasive P240-P320, achieving a perfectly smooth surface. The transition from the putty areas to pure metal should be smooth, without sharp steps. Only after achieving the ideal geometry can you move to the priming.
Surface surface substrate of detail
The grounding is the link between the metal/patty and the finishing. Primary soil (phosphate or epoxy) is applied to bare metal to prevent corrosion and provide chemical bonding. Secondary acrylic soil fills the risks from grinding and creates a uniform substrate under the paint.
The application technology involves the use of spray gun with a duse of 1.6-1.8 mm for acrylic soils. The material is applied in 2-3 wet layers with interlayer exposure indicated in the product technical map. Acrylic soil It has porosity, which must be closed correctly to avoid varnish failures.
| Type of soil | Appointment | Application | Suit |
|---|---|---|---|
| epoxy | Anti-corrosion protection | 1-2 layers | 24 hours / 60°C |
| Acrylic | Alignment, adhesion | 2-3 layers | 12 hours / 60°C |
| filler | Filling in the drawings | 2-3 layers | Instructions. |
After drying, the soil is grinded with an abrasive P400-P500 under enamel or P800-P1000 under metallic. Grinding should be performed "dry", since moisture that has fallen into the pores of the soil, when heated in the sun will turn into steam and cause swelling of the paint. Soil grinding requires special care so as not to wipe the material to metal or putty.
The quality of the final result depends on the quality of surface preparation and ground grinding, not on the brand of the paint itself.
Preparation for painting and coloring
Before applying the finishing coating, it is necessary to conduct final preparation, including degreasing and dust removal. The degreaser should be of high quality and not leave divorces. To remove microscopic villi and dust, sticky wipes are used that run over the entire surface immediately before painting.
Coloring paint is the process of selecting a shade corresponding to the factory color of the car. Even if you know the paint code, the actual color over the years could have burned out or changed the shade. Therefore, experts often do a “stretch” or test spray, comparing it with the body under different lighting.
- 🎨 Use computer selection to accurately hit the tone, taking into account the age of the car.
- 🌡️ The temperature in the paint area must be stable (about 20-22 ° C) for proper spreading.
- 💧 The humidity should not exceed 70% to avoid the mattage of the varnish.
Dilution of paint and varnish is made strictly in proportions specified by the manufacturer of materials. Using an inappropriate diluent (e.g., too fast or slow) can spoil the whole result by causing boiling, shaking, or long drying times. Solvent They are chosen depending on the temperature in the room.
Applying enamel and lacquer coating
Applying the base (metallic, mother of pearl or ordinary enamel) requires the skill of working with a spray gun. Keep the tool perpendicular to the surface at a distance of 15-20 cm, moving at a constant speed. Basic paint is applied in 2-3 layers with interlayer drying 10-15 minutes before mating.
After drying the base (usually 20-30 minutes) is applied varnish. The lacquer protects the pigment layer from ultraviolet light and mechanical influences, and also gives depth and gloss. Apply 2-3 layers of varnish, watching for uniform spreading ("bottling"). lacque It is a finish protection, and its quality directly affects the durability of the coating.
⚠️ Note: Do not try to save money on the lacquer. Cheap varnishes quickly become cloudy, yellow and lose gloss under the influence of sunlight and washing chemistry. Choose products labeled UV protection and high hardness (HS-varnishes).
It is important to keep clean in the working area, as any speck of dust caught on fresh varnish will spoil the appearance of the part. After applying the last layer of varnish, the detail is left to dry. The full polymerization time can take anywhere from 24 hours to several weeks, depending on the type of materials.
☑️ Quality control of painting
Polishing and finishing
Even with perfect painting, small defects may remain on the surface: “orange peel”, dust or accidental stains. Eliminate them by abrasive polishing after complete crystallization of the varnish (usually after 24-48 hours). The polishing returns the coating to a mirror shine and removes the drops of the shaking.
The process begins with the use of abrasive paste of the first number and a rigid polishing circle to remove the upper microlayer of lacquer. Then switch to softer compounds and circles to remove holograms and create a finishing gloss. Polishing requires caution not to wipe the varnish to paint, especially on the sharp edges of body elements.
The final step can be the application of ceramic coating or wax, which will enhance the hydrophobic properties and protect fresh varnish. Compliance with all stages of painting car parts ensures that the car will look like new, and the coating will last for many years without complaints.
How much dry does the paint and varnish dry?
The drying time depends on the temperature and type of materials. At room temperature (20°C), the paint “from dust” dries for 15-20 minutes, and the varnish for 30-40 minutes. Full polymerization for polishing is achieved in 24 hours. When using drying at 60°C, the time is reduced to 30-40 minutes for a full cycle.
Can I paint a car without a compressor?
Theoretically, you can use aerosol cans or spray guns with an electric compressor, but the quality will be lower. Professional result with a flat layer and the correct size of the torch is possible only at a stable pressure, which provides productive compressors with a receiver.
Do I need to remove old varnish before painting?
If the old varnish is matte, has cracks or detachments - be sure to remove to the ground or metal. If the coating is whole, it is enough to wrap it with abrasive P800-P1000, degrease and apply a new layer of varnish or paint (provided that the materials are compatible).