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topic 44924

MIL-STD-171 Finish or


Q. I'm quoting a part that calls out a protective finish or of MIL-STD-171. Does anyone know exactly what this protective finish is? Any help would be greatly appreciated. I've been searching through the MIL-STD-171 document and can't find a description of the process.

Dale Crawford
Buyer - Shenandoah, Virginia, USA


A. MIL-STD-171E Finishing of Metal and Wood Surfaces unfortunately has similar paragraph and finish numbering. The finishes mentioned are in Table V on page 19.

Finish is Manganese phosphating, DOD-P-16232 [ed. note: replaced by MIL-DTL-16232 [link is to free spec at Defense Logistics Agency,]], type M, Class 3, with no supplementary treatment.
Finish is Zinc phosphating, DOD-P-16232, type Z, Class 3, with no supplementary treatment.

See MIL-DTL-16232G PHOSPHATE COATING, HEAVY, MANGANESE OR ZINC BASE (the current specification) for details. Note that a chromic acid rinse is required.

Ken Vlach
- Goleta, California
contributor of the year honored Ken for his countless carefully
researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work
which the finishing world continues to benefit from.


A. designates a manganese phosphate coating and designates a zinc phosphate coating. See Table V in MIL-STD-171.

Toby Padfield
Automotive module supplier - Michigan


A. Bidder beware! Mil spec phosphate MANDATES submittal of the plater's phosphating procedure to the government's ultimate procuring activity, typically Rock Island Arsenal, for review and approval prior to awarding of the contract. I would be hesitant to have any job shop phosphating house unfamiliar with such government specs, particularly phosphating, from submitting pricing. Requires testing of baths and rinses every 4 hours, coating weight tests for every 8 hours, salt spray testing both before and after application of preservative, and on and on. You need a house familiar with this spec!

milt stevenson jr.
Milt Stevenson, Jr.
Anoplate Corporation
supporting advertiser 
Syracuse, New York

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March 10, 2008

A. MIL-STD-171E is soon to be replaced by MIL-STD-171F.
Consider MIL-STD-171 a shopping list of finishes.
Finish is a heavy manganese class 3 phosphate coating without supplemental oil and is a heavy zinc class 3 phosphate coating without supplemental oil. See MIL-DTL-16232G for the phosphate coating process requirements.

Note that specifications may be obtained at the following web page:

Type the number only (i.e., 16232, 171) of the spec in the second block "Document Number" and then hit return or click the "Submit" button... Note that supplementary treatments i.e., oil preservatives, dry film lubricants & CARC paints shall be traceable to the latest Qualified Products List (QPL) for the specifications or from the ASSIST Online Qualified Products Database (QPD).

Be advised that QPL's are currently being transformed to a Qualified Products Database (QPD).
To obtain the latest qualified products, apply for an account and password at ASSIST Online:
After logging in, click on "QPD" from the left-side list, then click "Search" type in the "Document Number (i.e., 3150)" and hit return or click the "Submit" button. Click on the "Specification (i.e., MIL-PRF-3150)" and view the qualified products by clicking on the listed "Govt Designation" numbers.
To order specifications (i.e., FED-STD-595) apply for an account and password at the "Shopping Wizard."

David Presto
- Rock Island, Illinois, USA

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