Aerosol paint in plastic cans: a complete guide

Restoration of plastic elements of the body or interior of the car is a task that requires a special approach, since standard enamel is often not kept on such surfaces. Plastic has a specific structure and low adhesion, which is why ordinary paint eventually begins to peel or crack at the slightest bending of the part. That's why. plastic-paint It should have increased elasticity and contain special adhesive additives.

The use of finished formulations in cans greatly simplifies the process, saving the master from the need to mix the components and select the proportions of the diluent. Modern formulas allow you to obtain a coating that in its strength and appearance is almost not inferior to the factory. However, even the highest quality canister will not give a result without proper surface preparation and compliance with the technology of layering.

In this article, we will discuss in detail how to choose the right product, how the compositions for different types of plastics differ, and what mistakes beginners most often make. You will learn why some parts require the mandatory use of soils and how to avoid the effect of “orange peel” when working from canned water.

Features of the chemical composition of paints for plastic

The main component that distinguishes plastic paints from universal enamels is the presence in the composition polymeric. Conventional alkyd or acrylic paints after drying form a rigid film, which when the base is deformed (compression or stretching of the plastic) simply bursts. The composition of specialized aerosols includes modifying additives that allow the coating to stretch along with the part.

It is important to keep in mind that plastics are divided into hard and soft types, and each requires different chemical formulas. For solid plastics such as ABS or polycarbonate, acrylic-based formulations are often used, which create a strong but not too flexible coating. For soft and flexible elements, such as bumpers made of polypropylene (PP) or bumper plastic, high-content enamels are needed. elastomers.

⚠️ Never use metal-labeled paints or universal enamels without first testing for flexibility. The coating can fall off with layers after the first wash or temperature change.

The solvent in such aerosols is selected so as to slightly melt the top layer of plastic, creating a diffusion effect when the paint penetrates the structure of the material. This provides the so-called chemical adhesionIt is much more reliable than mechanical coupling. That is why before buying a spray, always read the composition on the label, looking for notes on compatibility with the type of your plastic.

Classification and selection of suitable canister

The automotive chemicals market offers a wide range of solutions, and the choice of a particular product depends on the type of part being restored and the desired finish. The main separation occurs by the type of binder and the required finishing treatment. For professional results, it is important to understand the difference between single-component and two-component systems, even if they are packaged in an aerosol.

Single-component paints (1K) are ready for use immediately after shaking. They dry by evaporating the solvent and often require mandatory varnishing to protect against ultraviolet light and mechanical damage. Two-component aerosols (2K) have a capsule inside with a hardener that is activated before use. Such formulations form a harder and chemically resistant coating, but have a limited lifespan after activation.

When choosing a color, it should be borne in mind that special pigments are often used for plastic, resistant to burnout. If you plan to paint the salon, make sure the product has a label. Low VOC (low content of volatile organic compounds) to avoid toxic fumes in a confined space.

Necessary tools and surface preparation

The quality of the final coverage depends on 80% of how well the preparation is done. Plastic, especially secondary or used plastics, are often coated with silicone lubricants, antistatics and fats, which completely kill adhesion. The first step should always be to thoroughly wash the part using a degreasing agent specifically designed for plastics, for example. antisilicone.

After cleaning, the surface must be treated with an abrasive. For solid plastics, Scotch Bright or sandpaper with grain P400-P600 is suitable. Soft elements require a more delicate approach to avoid leaving deep scratches that will appear after painting. The main purpose of matting is to create a microrelief for mechanical engagement of the soil.

The final stage of preparation is the removal of dust. Use compressed air and a special sticky napkin to remove the smallest particles. If you skip this step, all the dust will be under the paint layer, and the surface will be rough. Antistatic This is critical because plastic is electrified and draws dust from the air even after cleaning.

Application technology: soils and enamel

The painting process begins with the application of adhesive soil (primer). It is a transparent or tinted composition that is applied in a thin fog layer. Its task is to penetrate the pores of plastic and create an intermediate layer to which colored enamel will stick well. For polypropylene, the use of such soil is a prerequisite, otherwise the paint will get peeled.

After drying the soil (usually 10-15 minutes), the main color is applied. Aerosol spray should be kept at a distance of 20-30 cm from the surface and make smooth movements. Technology wet by wet It allows you to reduce the drying time between layers, but requires experience to avoid causing leaks. Usually applied 2-3 thin layers with interlayer drying.

If you use paint such as "metallic" or "pearl", a finishing layer of varnish is required. Lacquer not only gives shine, but also protects delicate pigments from burnout and chemical exposure. For plastic parts it is better to choose flattening (Soft touch or plasticizers) that will not crack on the curves.

Typical mistakes when painting from spray

One of the most common problems is the appearance of a defect in the “orange peel”. This happens when the paint is too thick or the can is too far from the surface, and the solvent escapes in the air, before having time to spread through the part. To avoid this, apply the material in thin layers and monitor the temperature in the room.

The second common mistake is to ignore the temperature regime. Painting in the cold (below +15 ° C) or at high humidity leads to clouding of the varnish and long drying. Moisture can be preserved under the film of paint, causing subsequently swelling. Perfect temperature for working with aerosols is +20 ... +22 ° C.

⚠️ Warning: Do not attempt to accelerate drying with a building hair dryer or heat fan. The sharp heating can boil the solvent inside the film that has not yet formed, leading to craters and bubbles.

Also, beginners often forget about the activator in two-component cylinders or mix it poorly. If inside the balloon you can not hear the characteristic gurgle of the ball after activation, then the components have not mixed, and the paint will lose its properties in a short time. Always shake the balloon thoroughly within 2-3 minutes after activation.

Drying and polishing of finished coating

Complete polymerization of paint takes much longer than drying time "on the stick". Although the surface may appear dry after an hour, the chemical processes inside the layer last for several days. During this period, it is not recommended to wet the part or expose it to mechanical stress. Full strength of the coating is gaining in 7-14 days.

If after drying there are small dust particles or the shaven is too large, defects can be eliminated by polishing. However, this can only be done after the paint has been fully aging. Use polish pastes with P1500-P3000 abrasive and soft polishing. For plastic, it is important not to overheat the surface with polishing, so as not to deform it.

Properly selected and applied spray-paint It is able to completely hide the traces of repair and return the plastic to the factory appearance. The main thing is not to save on preparative materials and strictly follow the manufacturer's instructions on the can.

FAQ: Frequently Asked Questions