vinyl dye on top of vinyl already painted?

[gords@shaw.ca]

Hi there,

I have a couple of small interior pieces from my 67 Camaro to paint to match the rest of the interior.

These pieces are vinyl/plastic and already painted with an oddball color so I want to spray them over with the right color. Do I have to use plastic/vinyl primer? Or just sand and shoot the new paint onto it?

Thanks,

Gordon