[AMANOCC]

I just got the Manganese phosphate system from Vern Owens in south carolina, haven't used it yet, supposed to be the way to go for bolts...it leaves them the color of pencil lead. I'll post when I do my first batch. Black oxide has an oily finish to protect it, as alone it has very little rust resistance. The phosphate Vern sells stands up to a Military spec salt water test...