Is there anything I can apply to remove flux residue before painting, or is it just a wire brush and elbow grease? Does it even need removing? I'm running a gasless MIG flux-cored wire. Paint will probably be a zinc-rich one of some description
I would say get rid, clean metal is what paint likes, and if non-etch paint then a scuffed surface is best (for the paint to bite onto). Wire brushes tend to burnish a surface so I whizz over with sandpaper quickly if it's lost its key, only takes a sec.