Color over new undercoating?

[GaryR]

I had the shop that fitted all my fiberglass parts and get her ready for paint clean and undercoat as they went along. He used a Wurth-type hard black coating as he knew I intended on paining the body color everywhere. The undercoat was done months ago and is perfectly clean. Should I use a primer before color or just drop the urethane right on it? I planned on trying a small area as i'm doing the engine compartment 1st, but figured many have been down this road.

Thanks!

[962porsche]

with out a wurth product # i'm not sure what was used ? if its chip guard ? then you would use the same sealer as you would when refinishing the rest of the car before you spray the top coats .