The Last Stand of the web we knew & loved: no cost, no reg'n, no popups
As an Amazon Associate & eBay Partner: we earn from qualifying purchases

finishing.com -- The Home Page of the Finishing Industry

-----

sulfuric acid anodized luminaires turning yellow

2004

I work for a large electrical industry in India, One of our luminaire product [Halogen Flood Light] constructed from PDC Al. The internal Al fitment [99.7% pure] for the same is Sulfuric Anodized [Type II]. The sealing used is 5 - 10% nitric + boric acid dip. We are facing a problem of the internal Al fitting turning yellow on exposure to light [around 400 °C]. Any idea to overcome this problem of yellowing.

Regards,

Nilesh n. Oturkar
R&D Executive - Paint Technology - Mumbai, Mahrashtra, India

Aluminum How-To
"Chromating - Anodizing - Hardcoating"
by Robert Probert

Also available in Spanish

You'll love this book. Finishing.com has sold almost a thousand copies without a single return request :-)

"The Surface
Treatment &
Finishing of
Aluminium and
Its Alloys"
by Wernick, Pinner
& Sheasby
pinner

on eBay or Amazon
or AbeBooks

(affil link)

The problem with the anodized coating turning yellow when exposed to light relates to the failure of the seal and the components of the seal that you are using.

David B. Hunt
- Naperville, Illinois, US
2004

That strikes me as a strange sealing bath, Nilesh. Usually you would be using steam, boiling hot water, or a nickel acetate seal for that kind of application (in my experience).

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - 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: