Primer & Resins

I would use tamiya fine surface primer. It works on metal, plastic and resin. Comes in grey or white, the white makes a nice base to paint ferrari red. Should be about $6-7 a can at your hobby shop.

PS. Hey JimF maybe we're related!

 

My opinion here only refers to primers for resin and WM, not plastic.

I have used many many types of primers for resins and WM and found
that Tamiya white primer leaves a smooth surface that does'nt require
wet sanding and is the primer I mostly use. The Tamiya grey primer
requires a little rubbing out to create a smooth surface.

Ferrari used a red primer on their 50's and 60's cars so if you're doing
a red one from that era I suggest you use a red automotive primer.
Unlike the grey automotive primers, the red primer leaves a smooth
surface (almost as smooth as the Tamiya white). I use a red primer
for any car I'll be painting red. I have painted a red color coat over
white primer and over red primer and found the red primer to be the
best for that color.

 

And clean the resin with vinager to remove the sillicon of the casting