weld thru

what is the proper way to do this?

take paint to bare metal and quikly put on weld thru primer? can you weld to it with out peeling?

body filler will stick too this? you just dont want sand past the weld thru.

will high build primier stick to the weld thru?





also. would you guys rather...sand blast, or use paint stripper?
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take note that im seriously thinking of por-15ing the under cariage of the car, and it does have undercoating