paint finish

Hello, I have this vintage track frame and I'd like to change this colour red. I tried to use some solvent but it did absolutely nothing to it. It is very tick and hard coat. Would nail polishing work? How would you go about it? Thanks

I have this upper triple clamp (fork crown) that needs painting black and I'd like it to match the lower one (which is glossy). I've stripped the paint chemically and nearly finished getting the last of that off. Everything is sanded back, almost ready to go for the next step. Is this...