Restoring paintwork is a complex process that requires not only high-quality materials, but also strict adherence to technology. Acrylic paints today are one of the most popular solutions for local and complete repair of body parts due to their availability and ease of use. Unlike more capricious compositions, they forgive some mistakes for beginners, but still require a careful approach to surface preparation.
The success of the entire operation depends 80% on how well you prepared the metal before applying the first layers of enamel. Ignoring the degreasing or sanding steps will cause even the most expensive paint to bubble or peel after a short time. In this article, we will go through each step in detail, from choosing materials to final polishing, so that you can get a result that is not inferior to the factory one.
It is worth immediately noting that working with acrylic enamels involves the use of two-component systems where a hardener is added to the paint. This is a chemical reaction that cannot be stopped or reversed, so the components must be mixed immediately before use. Correct temperature and humidity in the paint booth also play a critical role in creating an even, defect-free film.
Selection of materials and preparation of the workplace
The first step to a quality result is purchasing the right consumables. You will need not only the paint itself, but also a whole arsenal of auxiliary liquids: degreaser, anti-silicone, transition solvent and polishing pastes. You cannot save on solvents, since cheap analogues may contain aggressive impurities that will ruin the structure acrylic coating.
Organization of space is the second critical point. Dust is a painter's main enemy. Even microscopic particles deposited on fresh paint will ruin the appearance of the part. The room should be sealed, with good ventilation, but without drafts that can blow in dust. It is recommended to moisten the floor with water to remove settled dust before starting work.
Use sticky napkins (tack cloth) immediately before painting - they effectively remove static dust that ordinary rags do not pick up.
To work you will need the following tools and materials:
- 🎨 Spray gun with a nozzle of 1.3–1.4 mm for the base and 1.5–1.6 mm for the varnish
- 🧴 Degreaser and anti-silicone in a spray bottle
- 🛡️ Respirator with carbon filters and protective suit
- 📏 Grinder with abrasives grade P80–P2000
Working without a respirator can result in serious exposure to solvent fumes. Ventilation of the room should be forced, and not natural, to ensure constant air exchange.
Technology for preparing the body for painting
Surface preparation is the foundation on which the entire result rests. If you skip the corrosion removal step or fill the dents poorly, the paint will only highlight the defects rather than hide them. The metal must be perfectly smooth and dry. Any pockets of rust should be stripped down to bare metal, using a rust converter if necessary.
Puttying is carried out in several layers if the defect is deep. Each layer must be completely dry before applying the next. After drying, the surface is sanded. For primary processing, use a coarse abrasive P80-P120, and for finishing - P240-P320. It is important to create a risk that the soil can cling to.
⚠️ Attention: Never apply putty to a greasy or wet surface - this is guaranteed to lead to peeling of the material after a few weeks of use.
After grinding, the body is thoroughly blown with compressed air and degreased. To do this, you need to use special lint-free wipes and two types of solvent: the first washes off the main dirt, the second (anti-silicone) removes the remaining grease film. Movements should be progressive, without reciprocating circular movements, so as not to smear the dirt.
☑️ Control of surface preparation
The final stage of preparation is masking. All elements that cannot be painted are covered with masking tape and paper. Pay special attention to the door joints, handles and moldings - the paint penetrates everywhere, and it will be extremely difficult to wash it later.
Application of primer and insulating layer
The primer performs two functions: it ensures adhesion (adhesion) of the paint to the metal and evens out the microrelief of the surface. For acrylic systems, a two-component acrylic primer is most often used. It fills sanding marks and creates a uniform surface. It is applied, as a rule, in 2-3 layers with an interlayer exposure of 10-15 minutes.
An important nuance is the selection of soil color. If you are painting the car in a light color (white, silver), the primer should be light gray or white. For dark shades (black, blue, red) use dark gray primer. This allows you to reduce the consumption of expensive base enamel and get a more saturated color.
After drying, the primer layer also requires sanding. If there are no obvious defects on the surface (dust, shagreen), it is enough to sand it with an abrasive P500-P600 under the base. If there are unevennesses, start with P320 and gradually move on to fine grains. The surface should become matte and smooth to the touch.
| Surface type | Recommended primer | Grinding gradation | Number of layers |
|---|---|---|---|
| Pure metal | Acid (phosphate) + Acrylic | P400-P500 | 2+2 |
| Putty | Acrylic filler | P320-P400 | 2-3 |
| Old paint | Acrylic primer-insulator | P500-P600 | 1-2 |
| Plastic | Primer for plastic (adhesive) | Can't be sanded | 1 |
Particular attention should be paid to the ends of the doors and bends. There the soil often runs off or lies too thin. Use insulating soil, if there is a risk of old colors or putty stains showing through the new paint.
Why do you need acidic soil?
Acid primer (wash primer) contains phosphoric acid, which chemically bonds with the metal, creating anti-corrosion protection. However, you cannot apply paint directly to it; a layer of acrylic filler is required.
Base enamel application process
Base enamel is the layer that gives the color to the car. In acrylic systems (base paint + varnish), this layer does not have a gloss and looks matte. The main task of the painter is to lay the base evenly, without stripes or different colors. The paint is diluted with a solvent according to the manufacturer's instructions, usually in a ratio of 2:1 or according to viscosity in a viscometer.
The first layer is applied "fog". This is a thin, translucent layer whose task is to provide adhesion to the ground. Do not try to paint the surface the first time - it will drip. Let it dry for 5-10 minutes. The second and third layers are applied more intensely, overlapping each other by 50% (on “wet”).
The movements of the gun must be strictly parallel to the surface. The distance from the torch to the part is 15-20 cm. The speed of the gun must be uniform. If you move quickly, there will be a “cracker” (rough surface); if you move slowly, there will be drips. It is important to maintain an angle of 90 degrees relative to the plane of the body.
After applying the base, it needs to be given time to evaporate the solvent (exposure). Usually this is 15-30 minutes at a temperature of +20°C. The surface should become matte. If there are glossy spots left on it, it means that the solvent has not yet come out, and it is too early to apply the varnish - it will boil and give defects.
Varnishing and creating a protective layer
Varnish is a finishing coating that protects the base from ultraviolet radiation, mechanical stress and gives a glossy shine. For acrylic paints, two-component varnishes are used (HS - high dryness, or MS - medium dryness). The varnish is mixed with the hardener strictly according to the instructions; violation of the proportions leads either to non-hardening or to brittleness of the coating.
The technique of applying varnish is similar to painting the base, but requires more caution, since the varnish is transparent and defects are less visible during the process, but are clearly visible after drying. The first layer of varnish is also made thin and dusty. The second layer is the main, wet, glossy one. It is this that creates the thickness and depth of color.
⚠️ Attention: When applying the second layer of varnish, avoid sudden movements and drafts - they can cause ripples (orange peel), which will then take a long time to polish.
Waiting time between coats of varnish is about 15-20 minutes. The varnish should “set” but remain sticky. If you wait too long, the adhesion between the layers will be broken, and the varnish may peel off in the future. After applying the finish, the car is left to dry.
The quality of varnish determines 90% of the visual perception of color and the durability of the coating - do not skimp on the quantity and quality of varnish.
Drying, polishing and removing defects
Natural drying of acrylic materials takes from 24 hours to several days, depending on the temperature. To speed up the process, infrared dryers or heat guns are used, but the temperature cannot be raised sharply - this will lead to boiling of the solvent inside the layer. The optimal mode is gradual heating to 60°C.
After complete polymerization (after 2-3 weeks the varnish reaches its final hardness), polishing is often required. Microscopic dust (garbage) or light shagreen is removed with abrasive pastes. Start with a coarser abrasive (P1500-P2000) to remove the defect, then move on to finishing polishing (P3000 and paste) to restore the mirror shine.
During the polishing process, it is important not to wipe the varnish down to the base, especially on the edges and corners of parts, where the layer is thinner. Use a polisher with adjustable speed, starting at 800-1000 rpm for paste work and moving to 2000-2500 for finishing.
- 🌡️Control surface temperature when drying to avoid bubbles
- 💧 Use distilled water when finishing polishing
- 🧼 After polishing, be sure to wash the car with shampoo
The final result depends on patience. Rushing at the drying or polishing stage can undo all the previous work. High-quality polished acrylic lasts for years, maintaining the brightness of the color.
Frequently asked questions (FAQ)
Is it possible to paint with acrylic over old nitro paint?
Strongly not recommended without careful testing. Acrylic solvents can be aggressive and “lift” old nitro enamel, creating wrinkles. It is necessary to test on a small area or use an insulating primer.
How long does it take for acrylic paint to dry on a car?
Touch-drying time is 30-60 minutes at +20°C. However, complete polymerization and strength gain occur within 14-28 days. You cannot wash your car with abrasive sponges during this period.
Do I need to sand the base before applying varnish?
No, the base enamel cannot be sanded. The varnish is applied to a matte, dried base. Sanding the base will disrupt the color structure and lead to spotting after varnishing.
What to do if varnish starts to drip?
If the varnish is still liquid, you can carefully collect a drop with the edge of a napkin. If the drip has already dried, it is removed only after complete drying (after 24 hours) by carefully cutting it off with a blade and then polishing it with P1500-P3000 abrasives.