They sell cans of spray on galvanizing that you can find in any welding or metal working magazine or possibly at Grainger or McMaster-Carr.
Not sure how well it works - but they have sold it for years!! I guess people keep buying it.
Welding galvanizing puts out some very nasty vapors - can't remember what - but know that precautions MUST be taken.
I am a strcutural....not welding engineer.