what type of paint did you use?
I went through some experimentation before getting it right.
I know you didnt ask about the process, just the paint, but i thought id elaborate
used a white, plastic specific primer for about 4 layers
Acrylic paint, each color is a different brand, i cant remember them, for about 6 layers, light sanding in between each layer
then lastly, used an outdoor, weather/waterproof, flexible clear super gloss topcoat, for about 3 layers,
its completely water proof now,tested dumping water on it, with flex just in case the highback bends so it wont crack, and pretty strong, I tested it on brick wall and it barely scratched the topcoat