The car body is daily exposed to aggressive environmental influences, and over time even high-quality coating loses its original appearance. Small scratches, matteness, pigment burnout and loss of color depth are natural aging processes that every car owner faces. Often the only way to return the car presentable appearance and protect the metal from corrosion is to re-apply the varnish on the car, which requires strict compliance with technological standards.
The process of restoration of the lacquer layer is not just a cosmetic procedure, but a complex chemical and mechanical process that requires an understanding of the properties of materials. lacque performs the function of a barrier that protects the colored layer (base) from ultraviolet light, moisture and mechanical damage. If this barrier is broken or has completely lost its properties, ignoring the problem can lead to expensive repairs of the entire body element in the future.
In this article, we will discuss in detail all the stages of work, from diagnosing the condition of the old coating to the final polishing. You will learn in which cases local repair is enough, and when a complete repainting of the part is required. Proper surface preparation is the key to the durability of the new coating, and it is at this stage that the most mistakes are made, which subsequently cost the masters dearly.
⚠️ Warning: Never try to apply a new layer of lacquer over the old one without first grinding and degreasing. The absence of adhesion will lead to the fact that the coating will peel off in pieces after a few weeks of operation.
Diagnosis of the condition of the paint coating
Before purchasing materials and starting work, it is necessary to objectively assess the current condition of the body. Visual inspection in good lighting allows you to identify defects such as: oxide, deep chips or detachments. If the varnish simply faded and covered with a network of microcracks, but firmly held on the base, the situation can be corrected by polishing or applying a new layer after matting.
However, there are situations where simple cosmetics can not do. If you observe paint bloating, bubbles or lacquer detachment to metal, this indicates a violation of the technology of previous repairs or moisture getting under the coating. In such cases corrosion It can already develop under a layer of paint, and applying a new varnish only preserves the problem, which will resurface very soon.
For accurate diagnosis, professionals use a thickness meter that helps determine the number of layers and their overall thickness. If the device shows a critically thin layer or, conversely, an abnormally thick “cake” of paint and putty, the approach to repair should be individual. Local repairs It is possible only if the transitions between the old and new coatings are properly smeared.
Tools and materials selection required
The quality of the result depends on the materials used. For professional recovery, you will need a two-component acrylic varnish, which consists of the varnish itself and the hardener. It is important to choose products from proven brands, such as Mobihel, Brulex or ReoflexCheap analogues can quickly turn yellow or lose their shine when exposed to the sun.
In addition to the varnish itself, the correct selection of abrasive materials is critically important. To prepare the surface, sandpaper of various grains will be needed: from P800 for rough grinding to P2000-P2500 for finishing. It's also necessary. degreaser (antisilicone), a sticky wipe to remove dust and a solvent for washing the spray gun.
The table below shows the main components and their purpose so that you do not get confused when buying:
| Materials | Appointment | Features |
|---|---|---|
| Lac 2K (HS/MS) | Formation of a protective layer | HS - high dry residue, MS - medium |
| Hardener | Polymerization of lacquer | Selected by temperature (fast, medium, slow) |
| Solvent | Dilution and washing | Used 646 or specialized 650th |
| Antisilicone | Degreasing | Removes oils and silicones before application |
Do not forget that to work with a spray gun requires a compressor with a receiver that can give a stable pressure. Cheap models are often spit, which creates defects on the surface. Krascopult With a duse of 1.3-1.5 mm is considered the best choice for varnishing, providing a small spray torch.
Preparation of the surface for varnishing
The most important stage, on which 80% of the success of the whole operation depends, is preparation. Even the most expensive lacquer will not hide the shortcomings of preparation, but only emphasize them. The first thing you need to thoroughly wash the car, removing bitumen stains and metal dust with the help of special cleaners. After cleaning, the surface should be completely dry.
Then comes the matting process. If you apply the varnish to an old but whole layer, it must be skinned to create a risk for adhesion. Usually used abrasive P1000-P1200. The main task is to make the surface matte, removing the gloss, but not to wipe the paint to metal. If required localizationThe boundaries of the transition should be as smooth and imperceptible as possible.
☑️ Checklist of preparations
After grinding, the body is necessarily blown with compressed air, blowing dust from all joints, handles and moldings. Then degreasing follows: a napkin dipped in antisilicone, wipe the part in one direction, immediately wiping dry with a second dry wipe. The final touch is a passageway sticky-clothIt collects tiny villi and dust particles that are invisible to the eye.
⚠️ Warning: Do not touch the fat-free surface with your hands, even with gloves. Fat marks from the fingers can cause craters ("fish eyes") on fresh varnish.
Technology of applying lacquer coating
Making a mixture is a science that requires precision. It is necessary to strictly follow the proportions indicated on the bank by the manufacturer. Usually the varnish is mixed with the hardener in a ratio of 2:1 or 4:1, after which 5-10% of the solvent is added to obtain the desired viscosity. The resulting mixture must be thoroughly mixed and allowed to stand for 5-10 minutes to release air bubbles.
The application of varnish is carried out in 2-3 layers. The first layer is applied thinly, "sputter" to create a base and improve grip. Do not try to fill the surface immediately - this will lead to leaks. The second layer, often referred to as the “body”, is applied more wetly and abundantly, forming a basic thickness and gloss. If used HS-lacquer (high dry residue), often two layers are sufficient, as it is less susceptible to shrinkage.
What is “interlayer exposure time”?
This is the period that must be waited before applying the next layer. It is usually 10-15 minutes at a temperature of +20 ° C. The polish should become matte, but remain sticky. If you hurry, the solvent can boil under a new layer, creating bubbles. If you hold it, interlayer adhesion will be broken.
It is important to observe the temperature and humidity in the room. The ideal temperature for work is about 20-22 ° C. At lower temperatures, the varnish will dry for a long time and may lose its shine, and at high temperatures, it will catch too quickly, without having time to spread. Krascopult You need to keep perpendicular to the surface at a distance of 20-25 cm, moving at a uniform speed.
Add 5-10% Transition Blend solvent to the varnish if you are doing local repairs. This will make the transition from new to old polish smoother and less noticeable after polishing.
Drying and primary treatment
After the application of the final layer, the polymerization process begins. The car should dry in a clean, dust-protected room. Natural drying can take anywhere from 12 to 24 hours depending on the type of hardener and air temperature. Using infrared lamps or drying in a chamber at 60°C can reduce the time to 30-40 minutes, but requires caution not to overheat plastic or old paint.
The full hardness of the lacquer does not come immediately. Although it may appear dry in an hour, the chemical reaction lasts for several days. During this period, it is not recommended to wet the car or expose it to mechanical stress. If you plan on polishingIt is better to wait at least a day, so as not to damage the soft layer.
Often after drying on the surface, you can notice small defects: adhesive dust (“shagrin”), small leaks or “orange peel”. This is not a reason to panic, as most of these flaws are eliminated by abrasive polishing. The main thing is to give the varnish enough hardness before starting processing.
Removal of defects and finishing polishing
Finish polishing is what turns a merely painted detail into a sparkling mirror. The process begins with wet grinding with an abrasive P2000 or P2500. Grind carefully, evenly removing the shaft and leveling the surface. It is important not to overdo it and not to wipe the varnish, especially on the ribs and sharp edges of the body.
After grinding, the surface will be matte and will not have a shine. To return the gloss, a polishing machine and pastes of different abrasiveness are used. First, a coarse paste is used to remove the drawings from the sandpaper, then a medium-abrasive and, finally, the finish to create a depth of color. Polishing circles must be clean, and the speed of rotation of the machine is selected for the type of paste.
The quality of polishing depends on the cleanliness of the room and tools. One grain of sand caught in a circle can ruin the whole work, leaving deep scratches.
The final step can be the application of ceramic coating or liquid glass. These formulations create an additional hydrophobic layer, facilitate washing and prolong the life of the varnish. However, they should be applied only after the varnish finally "rises", usually 2-3 weeks after painting.
How much dried varnish on the car?
The drying time depends on the type of hardener. When using a standard hardener at +20°C, the primary drying (from dust) takes about 1 hour. Full polymerization for polishing - 12-24 hours. The final hardness of the polish is gaining after 7-14 days.
Can I varnish without a spray gun?
Theoretically, there are varnishes in aerosol cans, but it is extremely difficult to achieve a high-quality, level layer without professional equipment. There is a high probability of shaking, leaks and unevenness. For serious repairs, the spray gun is mandatory.
Why did the varnish fade after drying?
This can be caused by several reasons: high humidity in the room, too low drying temperature, incorrect dosage of hardener or the use of a poor-quality solvent. Often the situation is saved by deep polishing.