High-quality painting of the car is not just a colored layer on the metal, but a complex technological process that requires accuracy and the correct selection of materials. Exactly. spray-paint determines the final visual result, the durability of the coating and its resistance to external influences. An error in choosing the type of enamel or its improper preparation can negate all efforts to grind and prime.
The modern market offers a huge variety of formulations, from classic acrylics to the latest water-soluble systems. For a master or amateur who decided to do body repairs on their own, it is critically important to understand the characteristics of materials. Incorrectly selected viscosity or incompatibility of components often lead to defects such as shaverina, matteness or peeling.
In this article, we will discuss in detail what types of enamel exist, how to correctly calculate the amount of material and customize the equipment. You will learn about the intricacies of working with different chemical compositions and understand why. HVLP spray guns are often preferred over convection models for garage use. A competent approach to the choice of paint is half the success of the entire paint campaign.
The main types of automotive enamel for spraying
The first thing that a painter encounters when planning work is the choice of the type of paint material. Acrylic enamel (2K) is considered the gold standard for garage and professional repairs. They consist of two components: the paint itself and the hardener. After mixing, an irreversible chemical reaction begins, so you need to work with such a mixture quickly until it is polymerized in the tank.
The second popular option is alkyd (1K). They are cheaper than acrylic and easier to apply, since they often do not require dilution with a hardener, dry due to the evaporation of the solvent and reaction with oxygen. However, their wear resistance and gloss are significantly inferior to two-component counterparts, which makes them less suitable for full body painting, although they are quite suitable for hidden cavities.
⚠️ Warning: Never mix acrylic and alkyd paints in the same layer. Their chemical composition is incompatible, which will lead to swelling of the coating and the formation of ineligible defects on the surface of the body.
Special attention should be paid to water-soluble paints, which are gaining popularity due to environmental friendliness. They require specific equipment with Teflon pads and humidity in the chamber. For a beginner, it is better to start with classical solvent systems based on squirrelSince they are more progiving to errors in setting up the torch.
Calculation of paint flow and preparation of the mixture
One of the main problems when buying materials is the question: how much paint is needed for the element or the entire body? The consumption directly depends on the cover of the pigment, color and type of spray gun. The standard calculation for a complete repainting of a passenger car in one color is about 4-5 liters of the finished mixture, including soil and varnish, if we talk about a full cycle.
When preparing a mixture, it is critically important to observe the proportions indicated by the manufacturer on the bank. Usually the ratio is 2 parts paint to 1 part hardener (2:1) or 4:1, plus 10-20% solvent to achieve working viscosity. To measure accuracy, use measuring cups with calibration, rather than pouring components "by eye".
☑️ Preparation of the mixture for work
Viscosity is a key parameter for a spray gun. Too thick paint will lie “orange peel”, and liquid will flow. Use a viscometer (funnel) to check, the leakage time should be approximately 18-22 seconds for most acrylic enamels at a temperature of 20°C.
Remember that after adding a hardener, you have a limited time known as the “mixture viability.” Usually it is 2-4 hours, after which the material begins to thicken and loses its properties, becoming unsuitable for application even if diluted with a solvent.
Selection of spray gun and equipment configuration
The quality of the finishing coating depends on the tool by 50%. For automotive work, the best choice is the spray gun system. HVLP (High Volume Low Pressure). They carry up to 75% of the material to the surface, minimizing fog and paint savings, which is especially important when working with expensive pearl enamels.
The second popular type is LVLP (Low Volume Low Pressure). These pistols require less air at the inlet, allowing them to be used with less efficient compressors while maintaining a high quality torch. Cheap convection models for finishing the body painting are not recommended because of the low transfer coefficient and high risk of shaking.
The spray gun setting includes three main parameters: pressure at the entrance, the shape of the torch and the supply of material. Pressure is usually set in the range of 2-2.5 atmosphere (at the exit of the gun), the shape of the torch is regulated by the top screw, and the feed is regulated by a side trigger or screw.
Before starting work, be sure to conduct a test spraying on a test card or cardboard. This will allow you to assess the size of the drop, the uniformity of the torch and the absence of spitting. Only after making sure the stability of the tool, you can start applying paint to the body.
Technology of application and drying of coating
The painting process requires a strict sequence of actions. First, a binder layer (fog layer) is applied, which provides adhesion. He lies half dry, without gloss. After 10-15 minutes, after the solvent evaporates, the main cover layers are applied.
Each subsequent layer should be laid by 50% overlapping the previous one (the method is “wet wet” or interlayer drying, depending on the type of paint). It is important to keep the gun perpendicular to the surface at a distance of 15-20 cm and move at a uniform speed. Abrupt stops or a change in the angle of inclination will lead to inflows.
| Parameter | Base layer (Basecoat) | Lac (Clearcoat) | ground-enamel |
|---|---|---|---|
| Number of layers | 2-3 layers | 2-3 layers | 2-3 layers |
| Interlayer drying | 10-15 minutes | 15-20 minutes | 20-30 minutes |
| Pressure (atm) | 2.0 - 2.5 | 2.5 - 3.0 | 2.5 - 3.0 |
| Viscosity (sec) | 18-20 | 20-22 | 22-24 |
Drying is the final stage that determines the hardness of the coating. Natural drying at 20°C takes 24 hours to complete polymerization, although the paint will dry in an hour. Using IR drying or heating in a chamber at 60°C speeds up the process and increases the strength of the layer.
Painting defects and methods of their elimination
Even experienced craftsmen face defects if the technology is not followed. One of the most frequent. quill ("Orange peel"). It occurs due to too thick paint, high pressure or incorrect spraying distance. Small pearls can be removed by polishing, deep - only by grinding and repainting.
Another problem. quill Or bubbles. They are formed if the solvent does not have time to leave the lower layers before applying the next, or if drying between the layers was too short. In this case, only complete removal of the defective layer helps.
⚠️ Warning: If you notice dust particles hitting fresh paint, do not try to remove them with your finger or cloth right away. Wait for the full drying out, or you will smear the material and create craters.
The matteness or “blushing plaque” often indicates moisture getting into the paint or working in a room with high humidity and low temperature. To prevent this, use special evaporation slowers and watch the dew point in the paint chamber.
Safety and personal protective equipment
Car paints and especially hardeners contain toxic substances, the vapors of which are dangerous to health. Working without a respirator with activated carbon or class A carbon filters can lead to serious poisoning and chronic respiratory diseases.
In addition to the respiratory system, it is necessary to protect the skin and eyes. The isocyanate vapors contained in hardeners can cause severe allergic reactions and chemical burns. Use a paint jumpsuit, nitrile gloves and safety glasses.
Why isn't a conventional respirator suitable?
Conventional petal respirators protect only from dust. To work with paint, filters labeled A (organic gases) and P (particles) are needed. Without a carbon layer, the filter is useless against solvent vapor.
Provide high-quality ventilation of the workplace. In garage conditions, exhaust ventilation is often used, removing paint vapors downwards, as they are heavier than air. Open flames and sparks in the room where painting is carried out are strictly prohibited due to the high fire hazard of solvent vapors.
Frequently Asked Questions (FAQ)
Can I paint a car in a garage without a paint camera?
Yes, it is possible, but it requires careful preparation. It is necessary to eliminate all sources of dust, moisten the floor, seal the gaps and organize supply and exhaust ventilation. However, the risk of dust falling on the finish line remains high.
Which is better for a beginner: 1.3 mm or 1.6 mm?
For applying the base and varnish is optimal Duz set 1.3. to 1.4 mm. The 1.6mm duz is designed for thick materials such as soil filler or liquid putty. To start, it is better to have two different guns or a replaceable duz and needle.
How much paint does it dry before polishing?
Although the paint may appear dry after a few hours, it is necessary to wait for full polymerization to be polished. For acrylic enamels, this is usually 24 hours at room temperature or less when forced drying. Early polishing will lead to clogging of the abrasive and heating of the surface.
Do I need to lay before painting?
I will. The soil provides adhesion (adhesion) of the paint with metal or old coating, and also levelles the surface and prevents corrosion. Painting without soil will lead to rapid peeling and the manifestation of defects.
What to do if the paint starts to thicken in the tank?
If less than 30-40 minutes have passed, you can add a little solvent of the same brand and mix thoroughly. If the mixture began to clump or turn into a gel, it can not be used - it is spoiled and subject to disposal.
Properly selected and applied car paint serves for decades, protecting the body from corrosion and preserving the aesthetic appearance of the car.
Always filter the paint through a special filter funnel before pouring into the spray gun tank, even if it is new. This will delay random clots and prevent dusa clogging.