I passivate mine with either a phosphate based cleaner (or Evaporust); you can use WD40 on non-critical (where you don't mind a little residue) parts to keep them from flash rusting when you get them out of the solution. The last tag I did is still rust free better than a year later, uncoated.
A tip - use steel wire to suspend the anode (sacrificial) side, not copper. I use Arm and Hammer baking soda detergent for the solution, a little goes along way. Don't let the part touch the sides or the bottom of the container (which should be plastic), battery chargers work great (10 amp is perfect for small parts). If you get ambitious, you'll need to step up the amperage.
Regards,
Steve