On Sat, 19 Apr 2014 06:11:17 -0700 (PDT), trader_4
wrote:

Any obvious issues with OP's
door that's causing the rusting?

I also wondered about that. If the galv. is compromised by abrasion or
such, they could rust. It happens in gavl. fencing.

Page middle:

http://www.mechanicsupport.com/galvanize.html