Make sure you scrub all mold release from the knob by using good strong detergent and a toothbrush before hitting it with primer..... Like Unkl sez, 1-Shot will stand the wear and tear without clearcoating,unless you are really proud of your paint job and want some extra layer for protection.....
i have some parts on my dash i want to paint. will the 1 shot hold up better then Krylon. they are small parts. hard to spray