[230Grain Repost] How to Parkerize (Maganese Phosphate) Your Face Off

[Yet Another Article I wrote for 230Grain.com]

Warning, and general safety tips:
Always perform this and all other processes involving caustic chemicals in a well ventilated area using the appropriate safety clothing and eye protection. Great care must be used when using flammable materials around fire to prevent injury or death. MisoStudios.com and the author, Miso Beno, hold no responsibility for any injury or damage that may result from this tutorial. I have made every attempt to insure the factuality of this article but still suggest that the end user try it on a something cheap and easy to replace before trying it out on that family heirloom.

If you kill yourself or ruin your stuff it is not our fault.

Air Compressor
Bead Blaster
Clean Rags
Carburetor Cleaner
Distilled Water
Plastic 5 Gallon Bucket Full of Fresh Water
Empty Plastic 5 Gallon Bucket
Magnesium or Zinc Phosphate Solution
Non-Aromatic Petroleum Based Oil
Outdoor Stove
Rubber Gloves
Latex/Nitrol Gloves
Stainless Steel Tank and lid
Stainless Steel Thermometer
Stainless Steel Wire or Nylon Cord

Introduction

Parkerization or “Phosphating” is a chemical process that uses a manganese or zinc phosphate based solution to darken steel with a matte grey finish and to make steel more corrosion resistant. The chemicals used in parkerization are less caustic and safer to contain that those used in the bluing process. While this tutorial uses zinc phosphate and an AK-47 magazine to demonstrate parkerization the principles illustrated also apply to manganese phosphate and most forms of non-stainless steels.

The original, blued magazine.

Preparation of The Phosphate Solution

Before anything can be phosphated the solution must be mixed from the concentrate. Every manufacturer concentrates their phosphoric acid to a different strengths and the end user will have to refer to their manual determine the appropriate water:concentrate ratio before proceeding. Place the stainless steel tank on the stove and set your stove up according to its instructions. Mix your phosphate solution in the empty plastic 5 gallon bucket to the appropriate strength then add it to your stainless steel tank leaving several inches from the top to allow for splashing and the addition of the parts to be phosphated. Before proceeding to preparing the magazine it is suggested that the tank is covered to prevent spilling and contamination.

An Important Note About Barrels
If a barrel is being parkerized it is important to protect the muzzle, bore, and chamber from both the bead blasting and parkerization solution. Allowing blast media, or parkerization solution to come in contact with the crown, chamber, or bore could result in a loss of major loss of accuracy or a permanently fouled chamber. The best way to ensure that the barrel is protected is to use a tight fitting rubber plug and/sealer on all of the barrel openings including any gas ports, the chamber, and bore. It is also recommended that the chamber and crown area of the barrel be avoided while bead blasting to prevent knocking the plugs lose or damaging any uncovered surface. If proper care is taken the firearm will retain its accuracy and functionality while looking like it had come straight from the factory.

The abrasive blaster is one of the most nessesary yet most uncommon piecs of tooling you will need for this project

Preparing The Metal Surface
Once the phosphate solution is ready it is time to prepare the surface for treatment. The first and most important step is to remove all oils from the exposed metal surfaces. Failure to properly remove surface grease and oil can lead to a mottled and less corrosion resistant finish. Carburetor cleaner is a popular degreasing agent because of its degreasing strength and widespread availability. In a well-ventilated area or outdoors, simply spray a liberal amount of carburetor cleaner onto the magazine and allow it to rinse the oil and grease off of the metal. Then with a pair of gloves and a clean rag wipe the surface off and look for any residual grease and oil on the metal. Once the metal has been completely degreased it should only be handled with clean and dry gloves to prevent reintroduction of oils to the metal surface.

Just before bead blasting would be the perfect time to start preheating the solution. Set the burners to medium heat to start bringing the solution to operating temperature (191-210F/88.3C-98.3C). While the preheating is taking place be sure to cover the solution and check it periodically to prevent the solution from coming to a boil. Once preheating has started all that’s left to do is to remove the original finish and any rust on the magazine. Take the magazine put it in the blast cabinet, and blast all of the original finish off until all that remains is bare metal.

I do apologize for the low quality of this photograph but trying to get light to pass through Plexiglas and dust is pretty darned hard.

Parkerize!
It is necessary to suspend the magazine from the bottom of the tank to prevent any sludge build up from affecting the final finish of the magazine. This demonstration uses stainless steel bailing wire because will not react with the parkerization solution unlike galvanized steel or copper. Simply cut off several lengths of wire and either pass them through the magazine or build a cradle to suspend it.

The stainless steel wire cradle without the magazine.200F is a nice safe operating temperature.

Now that all of the is hard work taken care of and our parkerization solution is at temperature the magazine is ready to be immersed. Simply rest it on its cradle and agitate the parkerization solution every 30 seconds. When the bubbling starts to slow down flip the magazine over and continue to gently agitate until the bubbling has finished. White sediments may start depositing on the surface of the magazine once the parkerization but is no cause for concern.

Note the healthy heaping of bubbles coming from the surface of the product and the immediate discoloration of the steel.

At somewhat regular intervals (I typical do 20-30 seconds) the parkerization solution should be agitated to prevent buildup sediment on the surface of your product.

After a few minutes the product should be flipped over so the areas that are in contact with the stainless wire can be better exposed to the parkerization solution.Once the bubbling stops you can remove your product from the parkerization bath. Remember, this stuff is hot and can burn the heck out of you so be sure to wear gloves and use tongs or some other tool.

Post Treatment

Take the blackened magazine and throw it in the fresh water bucket and allow any sediment to rinse off while the magazine cools. Then take it out and immediately dry it off using compressed air or a dry towel. Even though the magazine has its phosphate finish it lacks the oil it needs to protect it from rusting and it will begin to stain in as little as ten minutes if it is not dried and oiled immediately. To oil the magazine any petroleum oil will do, but it is strongly suggested that oils that have a strong odor should be avoided, as the magazine will smell like whatever oil is used for several weeks even if it has been dried. Oiling can be done in one of two ways, the preferred method is to allow the magazine to set in oil for several hours after its dry to give the oil time really soak into the parkerization and give a nice dark finish before wiping the magazine down. The alternate method is to wipe the magazine down with a heavy coating of oil and to let it set in a plastic bag for several hours then to wipe it dry. Both methods work well and will leave a nice parkerized product.

Not Photographed: My hands in the water cooling off for 5 minutes.

Remember how I said to wear gloves? Yeah, that's a really good idea because this thing is hot hot hot.

We're done! Wait, no I lied. Leaving the product wet like this will cause it rust since phosphate is just as effective at holding oil against the surface of the steel as it is water.

Aw, but it looked so good before! I want it to look like thaaaaaaaaaaaaat.

Well if you want it to look like "thaaaaaaaaaaaaat," then simply throw your recently dried part into your convenient bucket of non-aromatic oil. If you do not happen to have a convenient bucket of oil, then liberally apply some lightweight non-aromatic oil directly to the part via any method you see fit.

After the magazine has had a chance to soak the oil up (a few hours is preferred) simply wipe off the excess with a rag and you're done. Note the darker circles on the magazine feed lips; that's where they were spot welded to the magazine body. Heat treatment, changes in metalurgy, and areas that endure sustained high temperatures will show similar discoloration.

Discoloration
Differences in metallurgical properties, heat-treatment, rust and poor handling of the metal before parkerizing are all common source of metal discoloration. While the metallurgical properties and heat treat are beyond the end user’s control rust and handling are both correctable. Should the magazine end up with a large rust stain or fingerprints, simply start the parkerization process over from scratch. If only one area is blasted while the rest of the old finish is left on the magazine there is a strong possibility that the two sections will have very different tone and a distinct perimeter where the two sections meet.

Parkerization kicks ass and if you have the time, space, and money to do it. You should.  If you have any questions feel free to post on 230Grain.com or in the comments below and I’ll do my best to answer them.

Useful Links:
Lauer Zinc Phosphate Solution
Lauer Manganese Phosphate Solution
Brownells Benchtop Parkerization Kit
Brownells Shop Sized Phosphating Kit. (Also includes components for bluing)