I had done body work in the lower corners. Anytime I pull glass we have to clean the channel out, sand, fill where it needs, prime, paint, then install windshield.8)
Is that what your asking or is there a special primer thats supposed to be used before sealer?
The 67 was professionally install insurance job. I didn't see him use any "primer".
Matter of fact, I haven't ever seen a glass guy come out and use any primer or etch the glass!!