ForMatter/Finishes/coating/Parkerizing (manganese / zinc phosphate)
finish_coating_parkerizing

Parkerizing (manganese / zinc phosphate)

coating · patinated · parkerized, phosphate finish, Mn phosphate, Zn phosphate, MIL-DTL-16232 finish

A dull, gray-to-near-black, oil-absorbent crystalline surface formed when carbon steel reacts with a hot phosphate bath. Standard finish on US military M1 Garand, Beretta M9, M16 hardware. Reads as workmanlike, military-issue, oil-loving. The phosphate holds oil; the oil seals the surface.

Phosphate conversion coating per MIL-DTL-16232. Manganese parkerizing: hot bath of manganese / iron / phosphoric acid at 95 °C for 5–25 min; surface reacts to form crystalline manganese / iron phosphate ~5–25 µm thick. Zinc parkerizing: zinc-based bath, slightly lower temperature, lighter color. Both finishes are porous — phosphate crystals form an oil-retentive matrix. Sealed by immersion in light oil, the porosity holds oil for months / years. Hardness of the phosphate itself is low; corrosion protection comes from the oil-impregnated layer. Re-park is straightforward: strip oil, re-immerse.

character — matte gray to charcoal-black, oil-darkened, slightly rough crystalline, military-issue register.

Finish properties

  • levelpatinated
  • subcategoryphosphate conversion coating
  • Ra (µm)5.0
  • applies tometal

Incompatibilities

  • stainless steel — no iron available for the phosphate to react with
  • aluminum / brass — wrong substrate chemistry

Second life

reversibilitymoderate — most coatings can be stripped chemically (methylene chloride for paint, NaOH for some powder coats) or thermally / mechanically (sandblasting). Some specialty coatings (DLC, ceramic) require commercial-service strip.
blocks substrate recyclingno
renewabilityfield- to shop-renewable — most paint and clear coats can be touched up or re-coated in service; powder coat and PVD coatings require a coating-house re-application.

SSPC / NACE surface-coating standards; manufacturer technical literature for the specific coating chemistry.

Citations