Roof skim coat

I guess you are not planning on keeping the car for very long, applying bondo straight to the bare metal like that. My car has been "skimmed" by the PO. and had already started to rust under the skim coat after only a couple of years.

Depending on who you speak to they may say that bog should be applied directly to bare metal that has been roughed with at least 80 grit paper. It cant rust if the topcoat is continuous as there is no exposure to oxygen.

I asked about that and they said that after the skim coat is smoothed they apply a sealing/rust inhibitive primer. Then they apply the high build primer.