Topher, Primer Sealer is what goes down under the paint, just like normal primers. It just creates a barrier so "hotter" paints like Lacquers can be used without ruining the plastic body. It also does wonders sealing those seams so they don't ghost back up like that. Go to any auto parts store that carries Dupli-Color paints and grab a can, it'll set you back around $8, but it's a big can that will last for at least three models. Here's some shots of something that has multiple lines in it from a pie-cut section being removed, and you can't even see a sign of the work. Dupli-Color Primer Sealer is my best friend!