I used to buy fasteners in bulk from McMaster Carr and a local Auveco distributor and send them to a local plating company to have better coatings put on them. Some of the generic fasteners from McMaster and others didn't seem to be coated with very rust resistant coatings, not to mention they had different color/style coatings. We had everything brought to one common coating so everything matched and was protected better from corrosion.