i am gonna sand off all the old paint and paint my car flat black...instead of actually using real paint im just gonna use primer and call it good...but i was wondering if it would work on my plastic front bumber

 

Should work as long as the surface and any loose chips of paint are sanded down. The good thing with primer is if a area chips away, primer back on top of it

My personal opinion, but white primer is the easiest to get a even coat with and looks a little better in the end. The darker the color, the more you can see your spray pattern and tell it came from a can.

 

The bad thing with primer is, water eats right through it. You'll start to see rust forming on top of the primer. Unless you have a good coat of paint on there, the metal will be in danger. TRUST ME I KNOW!

 

If he's just primering a car, I think the primer cracking on the bumper and looking like crap is going to be the least of his concerns. The only primer that will really hold up to the weather is auto body grade epoxy. It is not cheap and must be sprayed through a gun. Anything else is going to be a sponge, like stroker said.

 

O_o...why would you do that? What is there to gain?