If you've ever looked closely at the fasteners on an old Harley-Davidson, you'll have noticed that many of them are dark grey or black in color. This is not the result of age or weathering, but was purposely done at the factory to prevent the corrosion of steel parts. The process is known as parkerizing and for the chemists out there, it is an electrochemical phosphate conversion process using either a zinc or manganese base. Even though that may sound complex, the actual process is cheap and easy to perform at home which just a few supplies. Most of which you can pick up at your local Walmart.
Here's your shopping list:
Hot Plate
Thermometer
8 Quart Stainless Steel Stock Pot
Stainless Steel Wire
2 Gallons of Distilled Water
Parkerizing Solution
I purchased Maganese Parkerizing Solution online from Brownells, but you can also find it at well stocked sporting goods stores as it is also used to refinish guns.
The first step in the process is to clean the parts you want to parkerize it is very important that the surface is free of dirt and oil. I used a two step process starting with blasting the parts with glass beads followed by a wash down with lacquer thinner. Once the parts were cleaned, I put them in the oven at 200 degrees to dry and warm up before parkerizing.
While the parts were warming in the oven, I mixed the parkerizing solution with distilled water in the stock pot. Make sure you add the parkerizing solution first and then pour in the distilled water second. The directions call for one gallon of distilled water per 14 oz of parkerizing solution. Since the parkerizing solution came in a 16 oz bottle, I found it easier to mix the entire contents of the bottle with 146 oz of distilled water.
Next heat the solution to 195 degrees using the hot plate. By the time the solution reaches 195 degrees, your parts will have reached a similar temperature in the oven. Using the stainless steel wire, suspend the parts one at a time in the solution.
The parts will begin to bubble as soon as they are submersed and will continue to do so until the process is completed. I mostly did small parts, so the process only took a few minutes for each part. When the bubbling is complete, remove the part and rinse with distilled water.
Now you have a few choices. The first is to impregnate the parts with oil by submersing them in an oil bath. This is the most common practice and what I did. If you want your parts to be really dark, you can also go right from the distilled water rinse to a dip in a black oxide solution. Painting the parts is a third option, but make sure to skip the oiling if you plan to go this route.
Here's the results after just being pulled out of the oil bath. Overall I'd say the parts are not quite as dark as what you would expect from a professional parkerizing job, but considering the whole process took less than an hour, I figured it was worth a try. Plus the parkerizing solution is reuseable, so I can always give the parts another dip if they start to rust.
