Question About Finishes

[jburg318]

What is the chemical composition of the salts used for:

(1) Smooth blued parts? (Finish on 1903a3 stamped parts)
(2) Parkerized parts? (Finish on arsenal refinished parts)
(3) parts that have a rough texture like parkerization, but have a black look to them? (I have seen this finish on 1903 parts)

Information

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[Emri]

(1) - A mixture of sodium hydroxide, sodium nitrate, and sodium nitrite dissolved in water.

(2) - Either zinc or manganese metal dissolved in a phosphoric acid solution which is mixed with water.

(3) - That is the metal surface preperation prior to blueing. Blueing will look like whatever the surface prep looks like. Polished looks bright, media blasted looks dull.


HTH,

Emri

[jburg318]

(3) - That is the metal surface preperation prior to blueing. Blueing will look like whatever the surface prep looks like. Polished looks bright, media blasted looks dull.

Emri,

This makes sense, I have read that in order to cut down on production cost and times manufacturer's (specifically Remington) stopped polishing parts before blueing them. Thanks.

Jon

[Chuckindenver]

originally.
the blued parts on A3,s were not polished, only debured, and black oxide coated. original formula..sodium hydroxide, amoniom nitrate, and cyanide mixed with water, heated to temp,
that formula is not in use anymore, and the one Emeri has listed is one of the ones used today.
the phosphate coated parts were shot peaned prepped, then manganese or Zinc phosphate coated, then cured in oil, or a chromiate curing oil, then oiled and or greased before assembly.
on a rebuild.
most parts to be refinished were sandblasted. then coated in manganese phoshate, or parts replaced...with the finish applyed by the manufacture of said part.