....To get even coverage on most steels with perma blue, the surface needs to be very carefully degreased! I usually clean the part with disc brake cleaner, or MEK then when dry, I bake it in the oven at about 150 degrees for 30 minutes or so. allow part to cool about five minutes until just cool enough to handle comfortably DON'T handle the parts with your bare hands at anytime during the process use disposable rubber gloves and change them often, rinse in very hot water scrub with Dawn detergent between coats and rinse in water hot enough that the surface drys as soon as it is removed from the water s Perma will coat even on most steels this way, but it won't necessarily be very dark and may take up to 10 coats to really even out. Super will usually give a nice deep black finish in 2 or 3 coats. I find that application with a wad of old pantyhose material helps keep color even. I also sometimes buff VERY lightly with 00000 steel wool after application but before rinsing. Remember, steel wool has a lubricant in it, so rinse then scrub with Dawn (which removes the oils) and apply the blueing while the part is warm to the touch. This technique also works well with all the cold process blues I have tried.
But like Tim says, the Oxpho works better and is not so finicky and ,well, his results speak volumns!
DG