MIL-STD-171 Finishing Of Metal And Wood SurfacesThis standard establishes and updates general finish codes and serves as a general guide to the selection of suitable materials, procedures, and system for cleaning, plating, painting and otherwise finishing of metal and wood surfaces.

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TABLE IV.  Cleaning methods 1/

Finish No.

Requirements

4.1

Abrasive blasting (Method I of TT-C-490)

4.2

Hot alkaline cleaning - for ferrous metals (Method III of TT-C-490)

4.3

Solvent cleaning (immersion or spray) (Method II of TT-C-490)

4.4

Phosphoric acid cleaning (alcohol, detergent or solvent type with detergent)

MIL-C-10578 (Method VI of TT-C-490)

4.5

Use finish 4.4

4.6

Emulsion cleaning (Method IV of TT-C-490)

4.7

Alkaline derusting (Method V of TT-C-490) Use A-A-59260.

*

4.8

Acid pickling

4.8.1

Sulfuric acid pickling.  Immerse the part in a solution consisting of 5 volumes

of sulfuric acid (66 Baume or 1.84 Sp Gr), 95 volumes of water, and

nonfoaming liquid inhibitor, as directed by manufacturer of inhibitor, at a temperature of 170 - 180 0  F (77 - 82 0  C).  After removal of scale

(indicated by a uniform gray color), remove part from solution, allow to drain, and then rinse in fresh circulating water at 170 - 180 0  F (77 - 82 0  C).

Immerse for 2 to 5 minutes in solution of 1 ounce (28 g) of sodium

dichromate and % ounce (21 g) of phosphoric acid (75% grade) per gallon

(3.8 l) of water, at 190 - 2050  F (88 - 96 0  C).  Discard rinsing bath when

combined sulfuric acid and iron sulfate reaches 2 grams per gallon.  After

surfaces are thoroughly dry, treat and/or paint as soon as possible.  (Note:

Where the steel parts will be used under stress cleaning by acid pickling is

not recommended because of hydrogen embrittlement.  Acid pickling is also

not recommended prior to phosphating or painting.

4.8.2

Acid pickling - other methods as specified in detail on drawing or in contract

4.9

Hot alkaline cleaning, nonetching, for nonferrous metals.  Use A-A-59146

material in accordance with specification

4.10

Vapor degreasing, N-propylbromide or use a solvent conforming to ASTM

D4080