There is still a problem with the after weld wire though, and that is rust. And any wire exposed to the outdoors will rust faster than an indoor cage. As it oxidizes it will look duller and duller and eventually will start to turn whitish in color. You can touch a piece of galvanized metal that has been left outside, and have the oxidation come off on your finger in one pass. If it comes off on your finger that easily, a bird can lick it off while climbing on the cage.
Breeders scrub their cages with vinegar and water a couple times a year.
The scrubbing washes off some of the old rust and the vinegar somehow retards new rust, but can't stop it completely. And of course the vinegar wash won't last long if the cage is left outside. I have heard of people sending their galvanized cages to a shop that does a powder coating type of paint job. I don't know how well that works, zinc tends to be a poor paint primer. The best situation would be to take the raw iron wire in to be nickel plated, and forget about zinc and paint altogether.