The paint restoration process (PPC) is a complex engineering task that requires not only artistic taste but also a deep understanding of chemical reactions. Quality of painting It depends on compliance with temperature regimes, humidity and cleanliness in the working area. Many car owners mistakenly believe that it is enough to simply apply spray paint to hide the chip, but a professional approach involves multi-stage surface preparation.
In this article, we will discuss how exactly the body elements are painted at professional stations and what can be done independently. Acrylic enamel Modern two-component varnishes require an accurate dosage of hardeners, otherwise the coating will either not dry out or will crack after six months. Understanding the physics of the process will help you avoid costly alterations.
Modern technologies allow you to recreate the factory coating, which is visually impossible to distinguish from the original. However, for this, the rules must be strictly followed. The critical success factor is not so much the paint itself as the quality of degreasing and grinding before applying the first layer. Ignoring these steps leads to peeling of the material and the appearance of defects.
Preparation of the work area and safety
Before any work begins, space must be arranged. Dust is the painter's main enemy. Even microscopic particles that have settled on fresh varnish will spoil the appearance of the part. In professional shops paint chambers with forced ventilation and air filtration are used. In garage conditions, it is important to minimize the circulation of dust by moisturizing the floor and closing the walls with polyethylene.
Human security comes first. The vapors of solvents and isocyanates contained in the hardeners of varnishes are toxic. Working without personal protective equipment can lead to serious respiratory diseases and allergic reactions. Respirator. With carbon filters of class A1P1 or A2P2 is mandatory, conventional medical masks are useless here.
⚠️ Warning: Never use open fire sources or sparkling appliances in the paint area. Solvent vapors are heavier than air and can accumulate at low points in the room, creating an explosive mixture.
Lighting also plays a key role. Dim light will not allow you to see the real color and possible defects of the spray. It is recommended to use high color daylight lamps (CRI > 90) to accurately assess the hue. metallic or mother of pearl.
Dismantling and machining of the surface
Quality painting is rarely done "on the spot". To obtain the perfect edge (spray) and access to hidden cavities, it is better to dismantle the part. Removal of handles, moldings and headlights avoids paint on foreign elements and provides a uniform coating of the ends.
Mechanical cleaning begins with the removal of old varnish and rust. If corrosion has penetrated deeply, stripping to pure metal is required. For this purpose, grinding machines with abrasives of different grains are used. Rough sweep The finishing is done with P80-P120 paper and the finishing is done with P240-P320.
It is important to create the right risk profile (incisions) on the surface. The metal will not provide adhesion (adhesion) with the ground. Grinding should be carried out by cross movements so as not to create deep furrows that will appear after painting.
☑️ Checking surface readiness
After machining, it is necessary to blow all the cracks and joints with compressed air. Dust clogged in the gaps between the panels, when drying, can pour out on fresh paint. Use special sticky wipes to finally remove the microdust before applying the chemicals.
Spattle and geometry alignment
If there are dents or deep scratches on the parts, you can not do without a putty. Modern polyester putty allows you to restore the geometry of the body with high accuracy. It is important to apply the material in thin layers, allowing each to dry to avoid bubbling and shrinking in the future.
The drying time of the putty depends on the ambient temperature and the amount of hardener added. Exceeding the norm of the hardener can lead to a change in the color of the putty and the appearance of spots on the finish paint, especially in light colors. Acrylic putty They are more elastic and less susceptible to cracking on vibrating elements.
Grinding the putty is the most time-consuming stage. You need to use a developing powder or aerosol to see where the material still needs to be removed. The goal is to get a perfectly flat plane without pits and bumps. Often for this purpose, a long grinding pad is used, which shows all irregularities.
The Secret to the Perfect Plane
Use the “rule” – a long metal ruler or a flat rack. Apply it to the surface of the light. The lights will show where the material needs to be added or removed. Visually, these changes are difficult to notice.
After leveling, the surface is re-surfaced with the abrasive P240-P320 to create risks under the ground. The boundaries of the putty should be smoothly decked so that the transition is invisible even to the touch.
Printing: the basis of durability of the coating
The soil performs two functions: it provides the paint adhesion to the metal or putty and creates an insulating layer. There are several types of soils: acid (phosphate), epoxy and acrylic fillers. Acid soils They are applied directly to the metal to protect against corrosion, but require overlapping with acrylic soil, since they cannot be applied paint.
Acrylic soil-filler (primer) fills the small risks from grinding and creates a homogeneous surface. It is applied in 2-3 layers with interlayer drying. It is important to observe the “window” of application – if you hold the soil, it will have to be re-formed, since it will lose adhesion with enamel.
Drying of the soil can take place naturally or in an infrared drying / chamber. Heat treatment speeds up polymerization and reveals possible defects, such as swelling of the putty. After drying, the soil is grinded with an abrasive P400-P500 under enamel or P800-P1000 under the base with a transition.
⚠️ Attention: Epoxy soil has excellent moisture protection, but poor adhesion to putty. Apply it only on pure metal or on top of acid soil, but not on polyester putty without an intermediate acrylic layer.
Paint and lacquer technology
The most important stage is the application of the basic enamel. The paint is diluted with a solvent in the proportion specified by the manufacturer (usually 2:1 or 3:1). The speed of the solvent is chosen depending on the temperature: fast for cold weather, slow for hot to avoid boiling.
Application occurs with a pistol with a duz 1.3-1.4 mm. The movements must be parallel, with 50% overlapping each passage. Distance to the detail - 15-20 cm. The first layer is made thin, "dusty" so that the base will clutch the ground. The next 2-3 layers are applied wet, but without the formation of leaks.
After drying the base (it should become matte, usually after 15-30 minutes), varnish is applied. Lacquer protects color from ultraviolet light and gives gloss. It is applied in 2 layers: the first thin, the second abundant, until the appearance of a characteristic glossy shine ("liquid glass"). Two-component varnishes (HS or VHS) are most resistant to scratches and chemistry.
Check the viscosity of the paint with a viscometer. It is difficult to determine the correct density by eye: too liquid paint will give underdrafts, too thick - "orange peel" (mashing).
It is important not to overdo it with the thickness of the layer of varnish. Excessive thickness can lead to clouding (xerox) or cracking in the future. The lacquer should spread on its own, forming a smooth surface.
Table: Selection of abrasives for different stages
To achieve a professional result, it is necessary to use the correct grain of grinding materials at each stage. The use of too rough abrasive under the paint will lead to the drawdown of the material and the manifestation of risks.
| Work phase | Type of material | Recommended grain content (P) | Purpose of grinding |
|---|---|---|---|
| Rust removal | Sandpaper / Circle | 80 - 120 | Removal of corrosion to metal |
| Handling of putty | Sandpaper | 120 - 240 | Geometry alignment |
| Underground training | Sandpaper | 240 - 320 | Creating Risks for Adhesion |
| Paint preparation | Sandpaper / Scotch Bright | 400 - 600 | Soil smoothing |
| Polishing (after varnish) | Polishing paste | 1000 - 3000 | Gravel and dust removal |
A properly selected abrasive under the ground (not larger than the P500-P600) ensures that the risks do not manifest through the paint after drying.
Pollination and elimination of defects
Even in ideal conditions, dust or a small shaft can remain on the varnish. The polishing returns the coating to a mirror shine. The process begins with abrasive polishing (cut), where the micron layer of varnish is removed, and ends with finishing polishing (finish) to remove holograms.
Use the polishing machine should be with caution. Overheating of the surface can cause the varnish to be wiped or the plastic underneath to deform. Turning the machine should not exceed 2000-2500 rpm, and the movements should be smooth, without strong pressure.
After polishing, the car is washed, removing the remnants of the paste, and protective wax or ceramic coating is applied. This will prolong the life of the new LCP and facilitate subsequent care. Full polymerization of the varnish takes from 2 to 4 weeks, so in the first month, it is not recommended to wash the machine with aggressive chemistry.
⚠️ Note: Do not polish your car immediately after painting. The polish should dry completely and gain hardness (usually 3-4 weeks). Early polishing will result in tightening of the varnish and loss of gloss after a short time.
How much paint does it dry in garage conditions?
The drying time depends on the temperature and type of materials. Basic enamel dries 15-30 minutes to matteness. The lacquer gains primary strength in 2-4 hours, but is completely polymerized (hardens) within 2-4 weeks. The process can be accelerated with the help of IR drying, but only after the evaporation of the main solvents.
Can I paint the part partially (stained)?
Yes, the technology of local repair ("in the spot") allows you to paint only the damaged area with a smooth transition to the old varnish. This requires high craftsmanship and special equipment (such as an airbrush or mini-jet) to blur the boundaries of color.
Why did the paint bubbles appear?
Bubbles (boiling) usually occur due to too rapid drying of the solvent, applying too thick a layer, high drying temperature or getting moisture/oil into the paint. Also, the cause may be insufficient drying of putty or soil.
Do I need to remove old varnish before painting?
If the old lacquer has no chips, cracks and holds well, it is enough to wrap it (make matte) with abrasive P800-P1000 or scotch bright. Complete removal is required only in the presence of serious defects or detachments.