Two-component paints (also referred to as 2K paints) are paint systems with two components in one paint mix. One component is the paint, and the other a hardener which reacts chemically with the paint when sprayed.
The result of this two-component system is that the paint dries harder and faster than a standard paint, because the dedicated hardener undergoes a chemical reaction with the paint, which causes it to harden and dry. This is different to a one-component paint, which dries in the air by solvent evaporation.
And so, the performance difference between a 2K paint and 1K paint is that 2K paint dries by chemical reaction, while 1K paint dries by air.
The benefit of a 2K paint is that in many cases, the paint will have better properties. It will be harder and therefore more durable than a 1K paint. It will retain colour better and have better overall film integrity, making it last longer.
One-part paints have come a long way, however. In a similar way to how certain one-part epoxies can outperform two-part epoxies, so too can one-part paints. One-part paints are also easier to work with, making them a better DIY option.
2K paints and UPVC
Although 2K paints have desirable physical characteristics, they are not wholly necessary for UPVC. A high-quality, solvent-based plastic paint will do just fine and in many cases when professionally applied, it will outperform a 2K paint.
It’s important that the paint bonds with the plastic on a molecular level. Plastic paints that simply adhere to the UPVC surface are no good and should be avoided at all costs. The paint needs to bond with the UPVC so the first layer sticks. Then, subsequent layers will bond with previous paint layers on a molecular level too.
Overall, 2K paint is suitable for UPVC but really not necessary. You can get a finish just as durable and with half the effort with a quality solvent-based plastic paint. For example, we stamp our work with a 10-year guarantee, and we use 1K paint.