Early A-bodies paint procedure!

In my work of getting my cack in shape I'm doing some research on the paint procedure. But I need to find out one thing;

when was the body sealer applayed? On the bare metal, on the red primer or on the green primer? Or was it a mix of it? I need help from someone that knows the procedure and how it was done. Any input in this would help me alot.

Thanks in advance