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


Prevention of White Rust in Aluminum Castings

Q. Good morning sir,

I am hemavathy, working as an executive in a die casting division which produces aluminium castings for automobiles and we have white rust formation in our castings. Our castings are stored properly and are safely packed in polythene covers. Could anyone please suggest me some useful ways to save the castings from the white rust.

With regards

G.D.Hemavathy Durairaj
- Chennai, Tamil Nadu, India

"Humidity Control Design Guide"

on AbeBooks

or Amazon

(affil links)

A. Hi. They perhaps are not chromate conversion coated or phosphatized; they should be. Plus, you need to keep them dry. Good luck.

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

A. Over the years I have experienced oxidation or white rust on aluminum castings after machining and washing them. Flare ups were usually in late summer (July, Aug) and in late winter (Feb, March). The primary culprit was humidity. Not many are aware that the late winter months are quite humid. The most effective way of dealing with these flare ups was to start using DI water for any operations ie. coolant mixing , washer recharge, etc. I am certainly not any type of expert, but the premise of DI was to eliminate or greatly reduce the chlorine content of any mixture coming in contact with the aluminum. It was not 100%, but it made a dramatic improvement.

Good Luck!

Pete Brown
- Petoskey, Michigan

A. Use alloy 360, has low copper, which has low potential for white corrosion.
Do not allow humidity in your parts, before storage.

A drop of water will be a spot of white corrosion.

Fernando Damasceno
- Sanford, North Carolina
October 8, 2009

A. VCI bags and VCI sheets can be used for packing and after machining. Running DM water can be used for washing.

Abdul Kadhar
- Chennai, Tamil Nadu, India
January 28, 2010

A. White rust forms on the surface of aluminum as a result of corrosion(actually oxidation). Chromation will be a better surface finish to prevent corrosion.

Anissh Jayaraj
Product design - Chennai,Tamil nadu, India
May 7, 2015

Q. I experience white rust during production of aluminum strip from the cold mill. What might be the cause of this? It's giving me so much concern, at first I thought the rolls were bad and caused friction with the strip but that doesn't seem to help too. Please advise.

Joseph ogochukwu
Caster and mill Engr - Enugu, Nigeria
March 17, 2018

Q. By any chance quenching operation can contribute to white rust in Silicon-Copper Alloy? Actually after solution treatment the parts are quenched in water then artificially over aged ... when checked in this condition there is no white rust, but after a few days... may be 10-15 days ... white rust is observed at customer storage location.

Madhan Kumar M.
- Chennai, Tamil Nadu, India
October 18, 2018

(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"