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topic 29417

Black oxide finish on Stainless Steel


A discussion started in 2004 but continuing through 2018

2004

Q. I would like to know how to "Blacken" stainless steel chemically? It will not react to parkerizing. I heard that a Sodium Dichromate or Potassium Dichromate Dip will work. Is this the only way besides painting it. I want to keep the restoration of firearms historically correct but perhaps up to date. I am mainly involved with Zinc Phosphate and Manganese Phosphate coatings.

Thank you,

Chris Conlon
Firearm Restoration - Avon, Indiana


"Firearm Blueing and Browning"
by R. H. Angier
from Abe Books
or
info on Amazon

2004

A. Cold black for SS:

1 lit H2SO4(1,55 gm/cm3)
Na2Cr2O7..........13 gms
temp.18-25 °C, 5-10 min.

Good luck!

Goran Budija
- Zagreb, Croatia


Need Sodium and Potassium DiChromate

2004

Q. [Where to get] Sulfuric Acid H2SO4 Sodium DiChromate Na2Cr2O7 Potassium DiChromate (to blacken stainless steel parts)

Chris Conlon [returning]
Firearm Restoration - Avon, Indiana
^- Sorry, this RFQ is outdated
     View Current RFQs



October 6, 2009

A. Hi, Chris. You should be able to find distributors of metal finishing chemicals in our Directory or the yellow pages of a nearby city. But you do need to know, in case you don't, that Goran's posting is intended for professionals who have received Haz-Mat training.

Dichromate (chromate, chromic acid, hexavalent chromium) are toxic and carcinogenic materials. And once you open them you become legally responsible for them forever. Most people have heard of Erin Brockovich and the attention being given to hexavalent chromium :-(

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey



BLACK OXIDE FOR STAINLESS STEEL 17-4

December 5, 2008

Dear Sir,

A tooling instrument using material 17-4, the process as follow:

1. Operation processes
2. Heat treatment to 40-45 Hrc
3. Bead blast
4. Black oxide coating

I am facing the problem of black oxide & blacken for stainless steel 17-4, that unable to cover the material surface cause wear off easily.

What about "special blacken", does it work?

What is the solution to do it like "blacken" the stainless steel 17-4?

I look forward to your reply soon. Thanks.

Regards,

Kent Ong
industrial user of metal finishing services - Malaysia


December 9, 2008

Dear Kent Ong,
I have few more questions in turn, to put forward here that would benefit the discussion.

1. Which method you do follow for blackening (Cold / HOT)stainless steel. (There are contradict view on possibilities for stainless blackening at room temperature)
2. What is the process (operating) temperature at which you carry out the Blackening process.

3. What is the least thickness of black oxide coat you tend to achieve, despite oxide scale thickness resulting from blackening process is not measurable in general.

4. How do you qualify the blackening process?
(If its Corrosion test, exposure time?).

Literature/Practical understandings:
1. Cold method can't be used for stainless steel.
2. 17-4 is a precipitation hardened stainless steel. Can there be direct correlation of aging temperature and blackening process temperature in altering material hardness / strength / corrosion resistance that results in wear.

KASI SUBBIAH PERICHIYAPPAN
- Bangalore, Karnataka, India


November 17, 2010

Hi, KASI SUBBIAH PERICHIYAPPAN

The Black oxide or Blackening done by supplier. I may lack of knowledge to answer that supplier did not exposure how the process do. Anyway you are giving the understanding.

To answer your questions as follow

1. As I know is HOT method for blackening.
2. Boiling temperature about 100 °C plus
3. Not thickness control, as long the part appearance is dark or black enough to meet.
4. There is no corrosion test on the part, but 17-4 is stainless steel would said cannot be corrosion so easily.

Regards
Ong

Kent Ong [returning]
- Malaysia



Cold blackening a Scotty Cameron stainless steel putter

July 14, 2018

Q. My situation:

I want to color a 303 stainless Scotty Cameron putter.
I've got the putter all dialed in and have sandblasted it
I then used stainless steel blackener from a hobby plating supplier after I put it in muriatic acid.
It came out all blotchy and just awful.

Could someone point me in the right direction.

Thanks,
Justin

Justin Davies
- Calgary, Alberta


July 2018

A. Hi Justin. Sorry, but I think the basic problem is the assumption that you can get a Scotty Cameron class finish on stainless steel from amateur cold blackening.

If you have the time to read them, you'll see that we have about a dozen threads on black finishes for stainless steel. They may be done with PVD processes, or sometimes specialty proprietary anodizing, or black chrome plating, or … maybe hot black oxide if done by professionals with experience and top quality carefully monitored and analyzed proprietary solutions (although even that is apparently questionable). But my guess is that cold blackening of stainless steel will never give you the quality you seek for a putter which costs hundreds of dollars.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



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