story and photos by frederick fortune home-brew...

Parkerizing is a method of protecting asteel surface from corrosion and increas-ing its resistance to wear through the ap-plication of a chemical conversion coating.It was perfected in the U.S. around theturn of the century and primarily used forarms and armaments in the military be-cause of its durability, part-to-part lubrica-tion qualities and its resultant ability tostand up to adverse climate conditions.

What it also does is provide a dark,beautiful, protective surface for smallparts that rivals the weather resistance ofmore expensive plating or coating tech-niques such as cad plating and anodizing.Many early motorcycle components wereParkerized as an inexpensive alternate tonickel, cadmium or later chrome plating.Unfortunately the process cannot be usedon non-ferrous metals such as aluminum,brass, or copper. Nor can it be applied tosteels containing a large amount of nickel,or to stainless steel or chrome. Everythingelse is fair game.

You need a number of things to do home-brew Parkerizing, but only 4 ingredients.

1. Pure Phosphoric Acid (85% Solu-tion), the active ingredient in rust re-movers, usually procured at a chemicalsupply house. A 500ml container costs$35-$50.

2. Powdered Manganese Dioxide (avery dense and heavy dark gray to blackmineral powder) also available at anychemical supply house.

3. Distilled water (I use tap water, butthe distilled supposedly gives more consis-tent results).

4 A biscuit of fine steel wool 000 or0000...dont use soap pads or Brillo pads!

I do this on a portable electric heatingelement using a one-gallon porcelain coat-ed metal cooker. Im told a Pyrex bowlwould work better but they are expensiveand breakable. Uncoated metal pots ap-parently wont work as well (if at all). Youwill also need a thermometer to gauge thewater temperature. While youre pickingup the chemicals, the same supply houseshould have those inexpensive 12 long labthermometers.

Proceed as follows:1. Use one whiskey jigger of Phosphoric

Acid per gallon of water. ALWAYS addthe acid to the water, and it is best doneby pouring it down a glass rod.

2. Add one whiskey jigger of the pow-dered Manganese Dioxide per gallon ofwater to the solution.

3. Bring the solution to an extremelyslow rolling boil. Best results are at or justunder the boiling point.

4. Now add your biscuit of steel wool.The steel wool will bubble and froth as itslowly dissolves. If your pot is too full ofwater, it may bubble over the sides.

Critical: The part(s) to be Parkerizedshould be totally de-greased and wirebrushed, sand or bead blasted prior to fin-ishing depending on the texture you desireon the finished part. Once you havecleaned the part, you should handle it withgloves, never greasy hands, and store itwrapped in clean paper towels awaitingthe Parker bath. Any grease or patina onthe parts or wire will cause a variation incolor...the parts will come out streakedand/or spotted. Be aware, too, that highcarbon or special alloy steels will nottake evenly. The only way to tell is to try.

Place a wooden stick across the top ofthe pot and suspend the parts in the solu-tion using steel or iron wire. DO NOT usepainted coat hangers or any wire withgrease on it! Ive also just carefully plunked

60 IronWorks May/June 2012

Rusted NutsSTORY AND PHOTOS BY FREDERICK FORTUNE

Home-brew ParkerizingAchieving the proper patina takes patience and practice

Before After

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61IronWorks May/June 2012

them in and stirred them around as theybubble with similar results.

The parts should be totally immersedin the solution, knowing that anywherethe wire touches the part or the partrests against the container will not be-come coated or may take a differenttone. If you cant cover them completely,turn them over continuously or, with anold squeeze baster, baste them like aturkey.

I usually let the part remain in the so-lution for a total of 30 minutes (shortertimes results in a lighter color, longer =darker). If you didnt suspend the part onwire, gently fish it out with clean pliers orwooden tongs. When you withdraw thepart, immediately rinse it in hot runningwater to remove the solution. If you useextremely hot water the already heatedpart will dry itself. Let it dry, getting coolenough to touch, on some clean papertowels.

The next part is magic. You can do itminutes or, as far as I know, hours later

but Ive been too impatient to wait. Hav-ing the part warm as possible is best be-cause things contract when they cool.Soak a clean rag in any type of cleanmotor oil and apply to the part, workingthe oil into the dark grey coating. Watchas the part takes on a deep, lustrouscharcoal black color. Let it rest and com-pletely cool down. When totally cool, takeanother clean rag and completely wipedown the part. A microscopic film of oilwill remain embedded in the coating mak-ing the part virtually waterproof and rustresistant. Bolts and nuts will stand up togentle wrenching without scratching,though they will scratch if roughly treat-ed. If scratched, sometimes a swipe ofoil will heal the wound.

For more on the history and science ofParkerizing, visit here:http://en.wikipedia.org/wiki/Parkerizing

Several caveats:1. Always be careful of any sort of acid,

even such an innocuous one as phosphoric.I never deliberately inhale the fumes al-

though there is no great odor to theprocess that I can tell. Just use commonsense, wear gloves and eye protection any-time you are playing around with chemicals.

2. Be very careful not to cause anysplashes with the boiling solution.

3. Prepare your area and your partsbefore hand, dont try to do this on thespur of the moment.

4. Once you have allowed the solutionto cool, you are done! Re-heating simplydoesnt work. Have everything that youwant to Parkerize ready to go when youfire up the solution. You can keep Parker-izing as long as the solution is hot, but forsome reason allowing it to get cold kills it...youve have to brew up a new solutionand start over from scratch.

5. If the surface is mottled, uneven orspotty it wasnt clean enough. You muststart over with clean, raw steel, wirebrushed and/or sandblasted...no rust,paint or oil film.

Use at your own risk. Your mileage mayvary. IW

Reader Service No. 33

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story and photos by frederick fortune home-brew...

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