Galvanized railing Will Sanding Remove Zinc and Make it susceptible to rust?

Question

I got my galvanized railing installed about 2 weeks ago and the contractors added touch-up paint but got smudged in some areas because it rained while the paint was drying. I asked the contractor about what to do about this and he said will have to sand the smudged paint and then re-paint those areas that are smudged. My question will sanding down the smudge areas remove the zinc and therefore make the railings susceptible to rust?

Answer 1

Yes, you can sand through the zinc, but you simply need to be careful.  The zinc is fairly thick.  If the guy is competent, he should be able to smooth the paint and keep the zinc intact.

Answer 2

The zinc is only a coating on the metal, much like a galvanized or paint finish.  You may grind it down to a thin coat, but will increase the risk of rust.  

Once sanded down, an additional coat of zinc or other exterior finish should be applied.  ASTM has standards for zinc thickness.