The appearance of a car consists of many details, and even the most expensive body paint can lose its attractiveness due to faded or scratched decorative elements. Moldings - these are the same plastic or rubber pads that are often the first to suffer from exposure to ultraviolet radiation, reagents and mechanical damage. Over time, gray, faded plastic begins to catch your eye, creating a feeling of unkemptness even in a freshly washed car.
The solution to the problem could be to completely paint the moldings in deep black, which will not only refresh the appearance, but also visually unite the disparate elements into a single style. This process requires patience and strict adherence to technology, since plastic is a capricious material and requires special approaches to adhesion. In this article, we will analyze all stages of the work, from dismantling to final polishing, so that you can complete the task at a professional level.
Doing the work yourself allows you to save a significant amount of money that would have to be paid to a body shop, but requires strict adherence to instructions. Errors at the stage of preparation or selection of materials can lead to the fact that the coating begins to peel off after just a few months of use. Therefore, before starting work, it is important to study the theoretical basis and prepare all the necessary tools.
Selection of materials and preparation of the workplace
The quality of the final result depends 80% on the correct choice of paint and varnish materials. Conventional enamels are not suitable for painting plastic, especially external body elements, since they do not have the necessary elasticity. You will need specialized paint for plastic with the addition of plasticizers, which will allow the coating to stretch and shrink along with the part under temperature changes.
Besides the paint itself, a critical element is adhesive primer. It is this that creates the chemical bond between the inert surface of polypropylene or ABS plastic and the finishing layer. Without this intermediate layer, the paint will form a film that will easily come off with pressure washing or light mechanical impact. Also don't forget about a degreaser and acrylic varnish to protect the color.
⚠️ Attention: Never use primers or paints that are not marked “for plastic”. The coating on such elements will inevitably peel off in the first winter due to the difference in the coefficients of thermal expansion of the materials.
The workplace must be clean, dry and well ventilated. Dust is the main enemy of the painter, settling on the sticky layer of paint and turning the smooth surface into “shagreen skin”. The optimal temperature for painting is from +18 to +22 degrees Celsius, and humidity should not exceed 60%.
- 🎨 Specialized paint for plastic (acrylic or polyurethane base).
- 💧 Adhesive primer for plastic (primer).
- 🛡️ Two-component acrylic varnish (if the paint is not matte).
- 🧽 Silicone-based degreaser.
- 🌬️ Solvent for washing the spray gun (646 or 650).
Dismantling and primary surface treatment
It is almost impossible to paint moldings with high quality without removing them from the car. Attempts to paint them “in place” will result in paint getting on the body, glass and seals, which will require complex and expensive cleaning. Therefore, the first stage is a careful dismantling elements. Depending on the car model, the moldings can be attached with clips, screws or double-sided tape.
Removing parts requires care, especially if the plastic is old and has lost its elasticity. Before starting work, it is recommended to warm up the elements with a hair dryer or simply leave the car in the sun so that the material becomes softer. This will reduce the risk of the mounting lugs breaking. If the molding is held on with tape, use a special adhesive remover or carefully trim the layer with fishing line.
After removal, it is necessary to remove all adhesive residues, bitumen stains and dirt. Ideal for this antisilicone or a specialized bitumen cleaner. Thoroughly wash the parts on all sides, including the back, since when painting the ends must also be treated to prevent corrosion under the paint layer.
☑️ Dismantling checklist
Mechanical grinding and matting
The smooth glossy surface of the plastic is not able to retain a layer of primer or paint. The main task of this stage is to create a uniform scratch (micro-scratches), which will increase the contact area and provide mechanical adhesion of the materials. This process is called matting.
For initial processing, use abrasives with a grit size of P400-P600. You need to work carefully, trying not to leave deep scratches that can appear through a layer of black paint. If there are deep scratches or chips on the moldings, they must be filled with a special putty for plastic, which is also highly elastic.
After initial matting and putty (if used), the surface is brought to perfect smoothness with P800-P1000 abrasive. It is important to understand that there should be no “bald”, untreated areas left. Even a small island of gloss will become a point of peeling in the future. It is convenient to check the quality of matting using a greasy finger: there will be no mark left on the matte surface, but it will be imprinted on the glossy surface.
| Defect type | Required abrasive | Processing method | Goal |
|---|---|---|---|
| Deep scratches | P240-P320 | Local grinding | Profile alignment |
| Glossy layer | P400-P600 | Full matte | Creation of adhesion |
| Putty | P600-P800 | Smoothing | Eliminating risks |
| Final matting | P1000-P1200 | Easy passage | Preparing for the ground |
The nuances of working with old paint
If there is old, but firmly adhering paint left on the moldings, it is not necessary to remove it “down to the plastic”. It is enough to thoroughly mat it with P800 abrasive, degrease it and apply an adhesive primer. However, if the old coating is swollen or peeling, it must be removed completely to the base.
Priming and preparation for painting
Applying primer is the foundation of your future coating. As already mentioned, for plastic moldings it is critical adhesive primer (primer). It is applied in a thin, semi-wet layer and serves as a connecting link. After 10-15 minutes, when the primer dries (“sticks”), you can apply the main acrylic primer.
Acrylic primer fills sanding marks and creates a perfectly smooth, uniform surface. It should be applied in 2-3 thin layers with interlayer drying for 10-15 minutes. Do not try to pour everything at once - this will lead to drips and a long drying time. After the primer has dried, the surface is matted again with P1000-P1200 abrasive to remove possible dust and shagreen.
Before applying the final color it is necessary to carry out final degreasing. Use lint-free wipes to avoid leaving lint on the surface. Movements should be confident, but without strong pressure. After degreasing, touch the surface with your hands strictly prohibited, since sebum will disrupt adhesion.
⚠️ Attention: Follow the interlayer drying time indicated on the can of materials. Under-dried primer under black paint can behave unpredictably, causing clouding or wrinkling of the finish layer.
Black paint technology
The most crucial moment is applying the pigment layer. Black color is the most demanding in terms of quality of preparation and application, since it shows any defects, dust and different colors. The paint should be applied in 2-3 layers, starting with a thin “spray” for better adhesion.
The first layer is applied using a semi-dry method so as not to cause drips on vertical surfaces. The second and third layers may already be more full, wet, but without fanaticism. Hold the spray gun or can perpendicular to the surface at a distance of 20-25 cm. Movements should be smooth, overlapping the previous pass by 50%.
If you use metallic or pearlescent paint (although for moldings they often use regular black or matte black), be sure to apply varnish. For regular black acrylic, varnish is also desirable, as it adds depth to the color and protects the pigment from fading. The varnish is applied in 2 layers according to the manufacturer's instructions.
- 🔫 First layer: thin, binding (dust).
- 💧 Second layer: wet, main (color set).
- ✨ Third layer (optional): for coverage and gloss.
- 🛡️ Varnishing: 2 layers with interlayer drying.
When painting with black paint, use a bright light source directed at an angle to the surface. This will allow you to immediately notice gaps or uneven application while the paint is still wet.
Drying, assembly and finishing
After applying all layers, the products require time to polymerize. Although touch-dry paint can dry in an hour, full hardness occurs after 24 hours, and final chemical resistance is achieved after a week. Do not rush to install the moldings right away; it is better to let them sit in a warm, dust-free room.
When installing, be careful with fasteners. If the moldings are attached with tape, use quality automotive double-sided tape (such as 3M). Before gluing, heat the tape and the surface of the molding with a hairdryer for better adhesion. It is better to replace mechanical clips with new ones, since old ones often break during dismantling.
Finishing may be required if dust has reached the surface. 3-4 days after painting, when the varnish has finally set, you can lightly polish with an abrasive paste to remove shagreen and give a mirror shine. This will give the moldings a factory look.
The main secret of success is not to skimp on drying time between layers and to use only specialized materials marked “for plastic.”
What is the difference between painting ABS plastic and polypropylene?
ABS plastic (often used for radiator grilles and hard trims) has a smoother surface and holds soil better, but is afraid of aggressive solvents that can corrode it. Polypropylene (soft moldings, bumpers) is very inert and requires the mandatory use of an adhesive primer, otherwise the paint will come off like a stocking. You can determine the type of plastic by the markings on the back of the part (ABS or PP).
Can you spray paint moldings?
Yes, for small elements and in the absence of a compressor this is an excellent option. The main thing is to choose a high-quality container of paint for plastic, shake it well (2-3 minutes) and practice on an unnecessary part to catch the spray torch. The application technique is the same: thin layers and drying.
How to remove small dust particles after painting?
If dust gets on fresh paint, nothing can be done until it has completely polymerized (at least a week). Then the defect is carefully ground with P2000-P2500 abrasive with water and polished with polishing paste. If there is a lot of dust, you may have to repaint the element.
Do I need to remove the rubber seals from the moldings?
Ideally, yes. Rubber and plastic have different structures, and paint on rubber will behave differently (it may crack or not dry). If it is impossible to remove the seal, it must be carefully sealed with masking tape, as close to the edge as possible so as not to get dirty.