Is this the right way to paint the plastic rear bumper?

[yukon]

on a 240sx hatchback:

rough up the existing paint and then prime using normal metal primer and then apply normal auto paint

I know there is a adhesion promoter for bumpers but since it is already painted I assume I would only need it if some of the bumper plastic was exposed?

I've been told that since the bumper is pretty rigid I dont need special paint or primer for plastic?

[FRoSt415]

if you want to do a shitty half ass job then paint wise thats it if you dont want to put any clear. sanding needs to get done before and after you apply the primer to remove sand scratches, then apply base coat and follow up with clear. i recomend if you did not do any repair work to the bumper meaing bondo, putty, glaze etc. then just sand with 400 and 600 with a block sander or orbital sander then apply primer, sand down primer with 800 and apply base, let that tack up for 30 mins to an hour or as directions say on can for applying clear coat.

[silpena]

just scuff it with a fine scotch bright, use an adheasion promotor, flexible primer then top coat with ur base paint and clear. do put to much clear. it will chip and crack from flex and road debris

[silpena]

just scuff it with a fine scotch bright, use an adheasion promotor, flexible primer then top coat with ur base paint and clear. dont put too much clear. No point, it'll just chip and crack easily

[shanes14]

if u are repainting it, then sand down the scratches with 320 then prime exposed plastic, or whole bumper, then sand primer after its cured with a minimum of 320 and paint.