What is Parkerizing?

Parkerizing or " Manganese Phosphating" is a metal finish/preparation that really gained popularity during WW2 when the US Government was looking to replace the typical blued finish on most small arms with a Rust Resistant and Anti Reflective coating that would be both Durable and Abrasion Resistant and hold up in all weather extremes, for this they chose Parkerizing or Phosphating with a Manganese substrate.

This process then gained widespread popularily within the automotive industry as an anti-corrosion technique for many small parts, especially critical exposed parts as in under carriage and under hood. Body bolts, suspension, and fasteners were but a few of the parts that General Motors (especially) Parkerized.

The Parkerizing technique is a Phosphate Etching process that produces a hard Matte or Dull finish that is both very Durable and Anti Reflective and with excellent oil holding properties. The Automotive industry quicky followed in step, seeking a cheap way to keep small steel parts from corroding, aside from expensive zinc galvanizing or eletro-plating. Also, black parts looked nicer on brackets and other visual components.

Grey Oxide may range from light grey to a darker grey depending on the type and hardness of the metal being applied to, whereas the Black Manganese will usually always be in the Charcoal Black range. We can do both! Either type of Parkerizing finishes will offer much more protection from exposure or harsh weather conditions, like salty air near the ocean. Gun Bluing, oxiding, or a selenic acid dip are inadequate for automotive/Marine applications and not OEM correct. A light application of oil on occassion is all it takes to keep a Parkerized part rust free.

Parkerizing is an immersion process requiring the manganese phosphate solution to be heated to approximately 190-210 degrees in distilled water. The boil out time can range from 5-45 Minutes, depending on the hardness of the metal and the desired thickness of the coating. As a rule, better grade steel takes a better finish. When the parts are finished to the desired coating, they are removed from the cauldron and directly immersed into HOT distilled water for a rinse. After a quick/forced air dry, the still hot parts are dropped into a thin machine OIL for 24 hours or more before installation.

Parkerizing can be used on any type of mild ferrous or hardened automotive grade steel/cast iron, the harder the better! It is not for use on stainless or any alloys of aluminum, brass, or copper.

The genesis and history of Parkerizing is quite fascinating! Google it up! Thank you Mr. Parker!!!

Back to Picture Page

Back to Main Page