Home /
T.O.C.
FAQs
 
Good
Books
Ref.
Libr.
Advertise
Here
Help
Wanted
Current
Q&A's
Search 🔍
the Site
pub Where the world gathers for
plating, anodizing, & finishing Q&As since 1989





-----

What causes blue discoloration of stainless steel





2004

Hi,

Can anybody tell me why a 304 stainless steel tank discolors and gets the light blue stains? .This tank contains dairy products. From time to time it is sterilized (vapor, 1300C for 30 minutes), and cleaned (sodium carbonate / washing soda [affil link] or sodium with a diluted acid).

The discoloration is superficial and can be wiped out using brush, cleaning agent or scotch-brite.

Thanks,

Shraga Yaron
- Hod Hasharon, Israel



2004

I believe it is some kind of chromium oxides.

Good luck

Cair Shishani
Khair Shishani
aircraft maintenance - Al Ain, UAE



2004

How do you get a vapor to 1300C? The blue normally is from oxidation caused by the high temperature and oxygen in the air. Organic material will bake on at this temp and will cause the blue to be very hard to remove as it is now an organo-metallic.

James Watts
- Navarre, Florida


none
finishing.com 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:

 
Jobshops
Capital
Equipment
Chemicals &
Consumables
Consult'g, Train'g
& Software


About/Contact    -    Privacy Policy    -    ©1995-2023 finishing.com, Pine Beach, New Jersey, USA