Tuesday, January 7, 2014

Parkerizing Metal

On vintage Harley Davidsons a lot of the small hardware, pedals, levers, etc. are treated against rust by the process of Parkerizing the metal.  I will be doing some of this as I put together the VL so I looked into the process as described below.

Parkerizing, also called phosphating and phosphatizing, is a method of protecting metal from corrosion by applying an electrochemical phosphate conversion coating. The process is frequently done on aluminum, brass, copper, stainless steel and other steel alloys -- particularly high in nickle. As such, the practice is mostly associated with firearms and firearm accessories, such as magazines. Essentially parkerizing is an improved form of zinc and manganese phosphating. It requires complete submersion into a solution of a phosphoric acid mixed with zinc or manganese and various levels of nitrates, chlorates and copper.


Things You'll Need

  • Steel object to be parkerized
  • Outdoor stove
  • 2 plastic 5-gallon buckets (one filled with fresh water, the other empty)

    • 1
      Set all of the materials in an outdoor or well-ventilated area. Parkerizing is an extremely dangerous process, so precautions must always be made before beginning. Once all the materials are in place and the outdoor stove is prepared, put the steel pot or tank on top of it.
    • 2
      Mix the phosphate solution. Check the manufacturer's instructions, including with the phosphoric acid, for the exact strength needed for the operation. Mix the appropriate amounts of acid and distilled water into the empty plastic bucket. Once the solution is at the appropriate ratio and well-mixed, pour the mixture into the pot or tank placed on the stove. Make absolutely sure to wear gloves and goggles when mixing or pouring phosphoric acid. Leave space at the top of the pot for bubbling, splatter and the volume of the metal object. 
    • Heat the solution to between 191 and 210 degrees Fahrenheit. The solution should be brought to just under boiling -- not actually boiling. Keep the solution covered while preheating and use the thermometer to keep track of the temperature.
    • 4
      Strip the steel of its original finish and clean it of any oil, grease, dirt or rust. Any substances leftover during the parkerizing process can lead to a less resistant result. This can be accomplished using a bead blaster, carburetor cleaner and clean rags.
    • 5
      Tie the nylon cord or steel wire to the object so that it can be safely moved while submerged. It's best to tie the cord or wire in multiple places, in a loose but secure way, so that the knots don't slip but the solution can fill the area under them.
    • 6
      Submerge the steel object into the solution after it has reached a steady, safe temperature. Approximately 200 degrees Fahrenheit is a good temperature to reach. Shake the pot or tank slightly every 30 seconds or so to make sure the solution gets everywhere on the object. The color of the object will begin to change -- a typical effect of the parkerizing process.
    • 7
      Flip the object over when the bubbling begins to slow down. Use the cord or wire to pull and maneuver the object, and the tongs to flip it over. Continue to shake the object around every 30 seconds until the bubbling stops. At times, white sediments may settle on the surface of the object. This is normal and should not cause worry.
    • 8
      Place the parkerized object into the fresh water bucket. Once the sediment is rinsed and the object has cooled, take it out and immediately dry it using a clean towel. If not immediately dried, the steel may begin to rust within 10 minutes.
    • 9
      Apply a thick coat of non-aromatic, petroleum-based oil. Do this by either rubbing the oil on and then placing the object into a plastic bag to soak, or by submerging it completely in the oil and letting it sit. Allow several hours for the oil to set into the metal.