To sand primer or not?

[Brumbach]

I've purchased the GCI paint and primer (red oxide III). I'll be doing the painting. Does the primer need to be sanded before I apply the topcoat? I've read many responses to this question on the internet and obviously the subject is controversial. Most say the purpose is to smooth out rough spots in the primer. This I understand. But a few comments claim the sanding is to ensure bonding between the primer and topcoat. Is this true? I suppose I might as well through in the question about the need for a primer sealer for good measure. Please share your opinions and experiences.

Thanks,

Bill

[jam51m38cdn]

What you wrote is exactly correct, wet sanding with 320 grit wet or dry smoothes the body and provides adhesion. I use a cellulose sponge, wet with a rubber sanding block and 320. This is what a body shop uses also. The rubber block is to get it straight and then I 320 wet sand all spots that I can`t get the block. Jim