No registration or passwords; no pop-up ads -- just aloha, fun, & answers.
(as an eBay Partner & Amazon Affiliate earns from qualifying purchases).
Home /
T.O.C.
Fun
FAQs
Good
Books
Ref.
Libr.
Advertise
 
Help
Wanted
Current
Q&A's
Site 🔍
Search
pub  Where the
world gathers for metal finishing
Q&As since 1989





-----

Blackodising of metal surface


January 17, 2011

Dear All

We are facing regular problems in blackodising of M.S. parts Some time they are z black but majority times parts are brown or some what rusty.

Can any one inform what is correct procedure of blackodising?
What type of chemicals used to get the black surface finish & is there any one who sell it?

Nitin Marathe
buyer of M.S. components - Belgaum Karnataka India



January 17, 2011

Hi, Nitin.

Yes, many companies supply black oxiding chemistry. It is distributed both by plating process distributors and by the gunsmithing industry. You haven't given us any information about what you are doing that would help anyone figure out why your parts come out brown or rusty instead of black.

The Metal Finishing Guidebook offers an introduction to the subject, and includes this formulation:
caustic soda [affil links] 80 oz/gal
Potassium nitrite 30 oz/gal
Potassium nitrite 20 oz/gal.

Remember that these very hot solutions (295° F) are very dangerous due to their propensity to "erupt" if the necessary evaporation losses are not made good properly but allow pure water (boiling point 212° F) to find itself in the body of the solution and suddenly flashing to steam.

Regards,

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



Parts rusting is almost always linked to an improper balance of water to salts. 99% of the time it's not enough water. The salts should be at a rolling boil with the temperature starting at 280 F and going up to 300 F as the water boils off. After the solution hits 300 F the parts must be removed and the salts taken back down to 280 F by adding water.

rod henrickson
Rod Henrickson
gunsmith - Edmonton, Alberta, Canada
January 28, 2011



January 4, 2012

We have just started BLACKODISING of MS,N8,N31,N24 materials.
(studs,Fixtures,nuts,packing plates)
We are facing following problems.

1.coating is uneven.
2.surface dose not shine.
3.it look brownish.

We use following mixtures
caustic soda [affil links]
sodium cyanide
water

Please help us to make it right.

Suraj Papde
- Pune, India




(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  -  ©1995-2024 finishing.com, Pine Beach, New Jersey, USA  -  about "affil links"