I built a deck and stair case using treated wood. On some of the posts for the staircase I used 1/2 x 6 galvanized carriage bolts. The rounded head of the bolt is on the inside of the stairs and the threaded part of the bolt is facing outwards. I cut off the remaining part of the threaded area and it is flush with the nut.
I'm looking for suggestions to coat the exposed part of the bolts to prevent rust.