I have a few parts that are made of blue plastic and I want to repaint them yellow. I plan on using Citadel (Games Workshop) Sunburst Yellow for the job, but I'm wondering if I should prime the parts first. While working on my animated Cy-Kill, I tried to paint the upper arms, which were molded in dark green plastic, using some Citadel brand paint (Red Gore). I primed the chest using some white Krylon primer thinking that when I would apply the red paint it would come out vibrant, but that wasn't the case. Instead, the red paint would barely stick to the primer and after several coats, all I managed to get was a pinkish color. I ended up removing the primer using alcohol and painting directly on the plastic. Despite not getting the exact shade of red I wanted, it was darker (too dark actually) the paint held much, much better. So before I start another project, I'm trying to plan ahead a little and figure out if I should use primer this time around and if so, should I use another brand than Krylon? Because so far Citadel Paint over Krylon primer = no good. It's too bad though, cause I really like Krylon paints. It's the first time I'm having trouble with them. Anyone out there has an opinion on the matter?