how to use weld-thru primer Options

[jmitro]

two questions about using weld thru primer, (assuming that proper usage is spraying primer on the backside of two adjoining pieces so that primer covers the bare metal that cannot be accessed once welding is completed);

1. Do you change the weld settings on the welder? It welds terribly with poor penetration. Or do you grind off the primer from the anticipated weld spot? If so, then it's defeating the purpose of weld-thru primer, is it not? it leaves bare metal.

2. After welding is complete, do you grind off the exposed weld-thru primer and replace it with POR-15 or primer of choice?

[larryM]

consider this expert advice
Ron Covell advice

"Q. I'm doing my own paint- and bodywork, Should I use weld-through primer for patch panels, or is it better to use a rust inhibiter after welding by dipping, or sealing, one side of the joint and flooding the other?

A. The answer to your question depends to some degree on the type of welding you do. TIG and gas welding are pretty sensitive to surface contamination, so these process would not be a good fit with weld-through primers, in my opinion.

If you are MIG welding, which is much less sensitive to surface contamination, you can make a case for using a good-quality weld-through primer. I've always preferred TIG welding, so the approach I'd take is carefully sealing the joint after welding."