The biggest mistake people make when painting plastic is choosing a paint that merely ‘sticks’ to the substrate. What you actually want is a paint that ‘bonds’ with the plastic on a molecular level so it cannot possibly peel away.
There is a massive difference between paints that ‘stick’ to plastic and those that ‘bond’ with plastic on a molecular level.
Paints that bond with plastic in this way undergo a chemical reaction that changes the shape of the paint molecules to those of the substrate. When looked at through a microscope, what you see is a molecular cross bond between them.
There is only one type of paint that achieves this form of bond, and that is specially formulated solvent-based paint. A good example of such a paint you can buy is Kolorbond for UPVC which is available online.
Other types of plastic paint can work, but they do not provide as durable a finish and especially on UPVC. UPVC lives outdoors, so the paint needs to be particularly resistant to UV and weathering. Paints that provide molecular adhesion are the best choice if you want to paint UPVC. We know this from experience.
Spray painting
It’s also important to point out that plastic paints applied with a brush do not have anywhere near the quality of finish as those applied with a spray painting gun. For a high-quality, factory-grade finish, you need to spray.
Not all plastic paints are suitable for spray painting, so you should check with the manufacturer. The paints we use are designed for spray painting, as is Kolorbond. If you are unsure about a product, err on the side of caution.
Lastly, aerosol paint cans are no good because they do not allow you to cover a large enough area rapidly. You could spend all day painting a window and not achieve the same finish as you would with a spray paint gun.
