Authoritative Answers, Fun, & Aloha -- no cost, no passwords, no popups
(as an eBay Partner & Amazon Affiliate we earn from qualifying purchases)

Home /
Site 🔍
pub     mobile?
Metal finishing Q&As since 1989


Phosphatizing standards -- MIL-DTL-16232

Q. Is there a QPL (document ID) for DOD-DTL-16232 [ed. note: replaced by MIL-DTL-16232 [from DLA] ]?

Mr. R. Andrew
- Phila. Pennsylvania

A. Hi R.

It doesn't appear that a QPL-16232 exists, and Section 3.1 "Preproduction inspection" of DTL-16232 seems to me to imply that there is no such QPL.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey
August 7, 2022

⇩ Related postings, oldest first ⇩

Q. Is Phosphatizing a standard process? Is there an industry or a Mil standard for this?


Suchart Pancharoen
- Lincoln, Nebraska

Surely! It all depends what type you want, and if you are the design source or a subcontractor. I'll cut-and-paste a typical list used in aerospace (MIL and AMS specifications):

  Conversion/Phosphate Coatings- AMS2473
  Conversion/Phosphate Coatings- AMS2474
  Conversion/Phosphate Coatings- AMS2475
  Conversion/Phosphate Coatings- AMS2480
  Conversion/Phosphate Coatings- AMS2481
  Conversion/Phosphate Coatings- AMS2485
  Conversion/Phosphate Coatings- AMS2486
  Conversion/Phosphate Coatings- DOD-P-16232 [ed. note: replaced by MIL-DTL-16232 [from DLA] ]
  Conversion/Phosphate Coatings- MIL-C-13924
  Conversion/Phosphate Coatings- MIL-C-5541
  Conversion/Phosphate Coatings- MIL-F-495
  Conversion/Phosphate Coatings- MIL-M-3171
  Conversion/Phosphate Coatings-Other
  Conversion/Phosphate Coatings TT-C-490 [from DLA]

Douglas A. Hahn
- Rocky Mount, North Carolina

MIL-DTL-16232 Class 4 Questions

Q. Hi, a client requested a class 4 zinc or manganese phosphate.

Reading the documentation MIL-DTL-16232 [from DLA] , I got confused with the statement:

Class 4
"Chemically converted (may be dyed to color as specified)
With no supplementary coating or coating as specified"

Looking for more information on what is class 4 I found that, according the paragraph 3.2.4d and 3.2.5, it shall not be treated in a chromic acid rinse. And that's clear for me.

In paragraph 3.7.3 and 3.7.5, for each type of phosphating class 4 systems, states that the phosphates that have been chemically converted by reaction with a reagent containing an inorganic salt, items shall be dyed to a specific color and should endure 72 hours of salt spray if supplementary treatment is applied, and 24 hours if no supplementary treatment is applied (Table II).

My issues:
  - What is the inorganic salt? Its something that is added to the phosphating solution? is post phosphating solution bath?

  - The dyeing process can be achieved by immersion in an aqueous aniline solution, just as an anodizing process?

My Zinc phosphate line use a commercial product (SurTec 610). And we been doing class 1, 2 and 3.

Thanks for the attention on this issue, I tried to look on the forums for this kind of topic before posting, but I could not find anything.

Best regards

Ivan Santos

Ivan Santos
shop employee - Sao Jose dos Campos, SP, Brasil
October 23, 2018

Q. I can only find the channel I am using in galvanized condition, can I still zinc phosphate the end product per MIL-DTL-16232 [from DLA] Type Z Class 3?

J Barge
Metals worker - Brighton, Michigan
October 15, 2021

A. Hi J. The phosphatization process should work. Galvanizing can be phosphatized essentially as described in MIL-DTL-16232. But it will be non-compliant with the spec, or at best questionably compliant, because the spec itself says its for ferrous metal, and it's probably a stretch to call a galvanized surface ferrous :-)

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey

(No "dead threads" here! If this page isn't currently on the Hotline your Q, A, or Comment will restore it)

Q, A, or Comment on THIS thread -or- Start a NEW Thread

Disclaimer: It's not possible to fully diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories:

Chemicals &
& Software

About/Contact  -  Privacy Policy  -  ©1995-2024, Pine Beach, New Jersey, USA  -  about "affil links"