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


Discoloration of MIL-5541 Alodine

June 10, 2022

Q. Hi, everyone

I am Morgan form Taiwan, and currently we are running a surface treatment shop.
We are now having the discoloration issue for the Alodine process.
We use the crane to do the dipping process for our product.
The advantage of the crane is that we can do more parts at once. But it pulls up the part at a very slow speed. When we pull up the part, the chemical flows over the part and causes the discoloration. Even if we keep spraying water on the part, it doesn't help.

Can anyone give us some suggestion?

Thank you in advance for the help.

Morgan Mao
- Tainan Taiwan

A. Hi Morgan. Apparently you've figured out that the problem is a lift speed that is too slow, but send photos to for posting if you wish.

It's not clear to me why you have to lift very slowly. Why not simply speed it up?

Luck & Regards,

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

A. I suspect the film is forming too fast due to low pH, high temp or high concentration. In a beaker, try raising the pH in increments of 0.1. This will slow the film formation, get it to about 90 seconds, then see if that helped the problem until you can do the recommended Mooney thing and speed up the hoist.

robert probert
Robert H Probert
Robert H Probert Technical Services
supporting advertiser
Garner, North Carolina
June 13, 2022

none is made possible by ...
this text gets replaced with bannerText
spacer gets replaced with bannerImages

(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"