Painting the plastic trim of a car interior with an aerosol has a few specifics. They concern the choice of materials and the surface preparation above all. Let us go through the process step by step.
Which plastics can be painted and which cannot?
A dashboard or a trim panel made of polyethylene, PTFE, silicone or polypropylene is almost impossible to paint — the paint either does not lay down at all or holds very poorly. These materials are rarely used for interior panels, but they do occur. Most other plastics in a car interior can normally be painted. Keep in mind, though, that there are tens of thousands of different plastics and some of them can surprise you. So if you are dealing with a material for the first time, it is best to spray a test area first.
Surface preparation
The surface to be painted has to be cleaned of dirt. If the plastic is hard enough, it is better to scuff-sand the surface with an abrasive pad: adhesion to a dull surface is always higher than to a glossy one. Degrease it with the universal degreaser KU-9102.
Priming
For better adhesion, apply one coat of Adhesive activator KU-6000 (with an alkyd paint this step is mandatory; with an acrylic one it is optional, but adhesion is higher with the activator).
If the surface has minor defects such as scratches or other shallow damage, apply the acrylic filler primer KU-220X or the universal acrylic primer KU-210X in a fairly thick coat. Once it has dried, sand the filler primer with fine sandpaper.
When priming interior plastic for metallic paint, it is important that the base is light and uniform in color. Metallics are fairly translucent, and every stain of the base shows through them. That is why the surface is primed either with the filler primer KU-220X, or with the gray plastic primer KU-6020.
One more priming option is the acrylic primer-enamel for plastic KU-60XX. As the name suggests, it works both as a primer and as a topcoat. It can go directly onto the plastic (or onto the Adhesive activator, or onto the acrylic primer) in several coats. That is all: the matt finish in one of the RAL colors is ready. And if the primer-enamel range has no suitable color, any paint you prefer can be applied over it.
Applying the paint
Plastic surfaces can be painted with acrylic, alkyd and cellulose ester (automotive metallic basecoat) paints.
The best materials for plastic are acrylic aerosol paints: the universal fast-drying gloss and matt RAL paint KU-AXXXX, the pastel matt paint KU-A10X and the silky SATIN RAL paint KU-0AXXXX. All of these paints are applied in 2-3 coats with 10-15 minutes of flash-off between coats.
Among the metallics the best choice is the cellulose ester automotive paint KU-4XXXXX. It has to be applied over a light, uniformly colored base in 2-3 coats.
Alkyd aerosol paints can go onto plastic only over the Adhesive activator KU-6000. Alkyd paints behave in their own way during application, drying and polymerization, so we recommend reading about them here first. Their limited flexibility does not allow them on soft and flexible plastics; they suit rigid, hard plastic parts only. Still, with all the difficulties and limitations, an alkyd paint on plastic is justified when you need the highest possible resistance to abrasion and solvents.
The choice of alkyd paints in the KUDO® range is wide. If you need one of the RAL colors, you can use the matt paint for profiled sheeting and metal roof tiles KU-0XXXXR or the gloss 3P TECHNOLOGY KU-1XXX. And if you need an unusual color, take a look at the alkyd automotive paint KU-4XXXX — it has a higher gloss, fades less and comes in more colors. All alkyd paints are applied in 2-3 coats with 10-15 minutes of flash-off between coats. Important! The maximum interval between coats must not exceed two hours, otherwise the finish will be ruined. Alkyd paints dry in 5 to 24 hours. Once dry, an alkyd paint keeps building hardness, strength and wear resistance for another two weeks. For these first two weeks after painting the part must not be contact-washed, polished or subjected to any other mechanical stress.
A separate word has to be said about the acrylic textured paint for plastic. It leaves a raised, textured finish that reproduces the original factory textures and hides unevenness and minor defects of the painted surface well. To start with, choose the paint KU-6206 with a fine texture or KU-6207 with a coarse one. Then adjust the distance from the can to the surface, the number of coats and the spraying technique so that the finish becomes indistinguishable from the factory one. The textured paint comes in black only, but it can be painted over if needed.
Topcoat – applying the varnish
The only coating that has to be varnished is the cellulose ester automotive metallic. The best choice here is the 1K acrylic automotive varnish KU-9010, and the universal acrylic KU-9002 and KU-9004 (gloss and matt) can be used as well.
Matt acrylic paints can be varnished for gloss and extra protection, but this is not required.
There is no point in varnishing an alkyd paint — it gives enough gloss on its own and beats an acrylic varnish in toughness.
