Home /
T.O.C.
FAQs
 
Good
Books
Ref.
Libr.
Advertise
Here
Help
Wanted
Current
Q&A's
Search 🔍
the Site

Chime right in! (no registration req'd)

-----

"Round White Spot after Anodising"





May 6, 2010

Hi,

Recently, we discovered that after potassium dichromate seal, there is this little round spot, anodised, on the surface. There is no color tone in this round spot of ~0.4 inch dia. Our process as follow;

Alkaline clean
Rinse
Nitric acid dip
Rinse
Sulpho Chromic etch
2X rinse
Sulphuric Acid Anodising
2X rinse
Potassium di-chromate seal @ 98 deg C
2X rinse
Air dry

Looking forward to your sharing

with Best Regards,

Jimmy Sim
plating shop employee - Singapore
^


First of two simultaneous responses -- May 10, 2010

You did not say the alloy. If is is in the 5000 series the spot could be raw magnesium that did not "alloy". If the metal is an extrusion or has been "cold drawn" then this white spot is probably elongated "round". Come on back with some more information and let's give it a guess.

robert probert
Robert H Probert
Robert H Probert Technical Services
supporting advertiser
Garner, North Carolina
probertbanner
^


Second of two simultaneous responses -- May 11, 2010

To answer your query, we would atleast like to know what you are anodizing. A picture would speak a 1000 words and maybe someone here could definitely help you spot the problem.

Winston D'Souza
- Bombay, India
^


May 17, 2010

My apology, the material is Al 6061 (I did try to upload the pic but it failed).

Jimmy Sim
- Singapore
^

----
Ed. note: just attach the picture in email to mooney@finishing.com, Jimmy.

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

Q, A, or Comment on THIS thread SEARCH for Threads about ... My Topic Not Found: Start 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    -    ©1995-2021 finishing.com, Pine Beach, New Jersey, USA