Aloha, fun & authoritative answers -- no cost, no registration, no passwords, no popups
(as an eBay Partner & Amazon Affiliate we earn from qualifying purchases)

Where the
world gathers for metal finishing
Q&As since 1989

-----

Yellow-Brown stain on Solution heat treated Aluminum

After solution heat treat of Various Aluminum Alloys (mainly 2024 and 7075) There is a yellow brown stain appearing on parts. (This stain seems to be more prevalent on bare alloys) The stain has an odor when the parts come in contact with water. The Salt bath is operated at 920 Deg F and is a mixture of approximately 50/50 Sodium Nitrate [affil links] and potassium nitrate. The stain easily comes off when the material is deoxidized. the stain is not always present , but when it is the smell is extremely unpleasant. Any ideas on what this stain may be?

Jim Morehouse
QA Engineer - Amherst, Nova Scotia, Canada
February 27, 2009

(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: