finishing.com -- The Home Page of the Finishing Industry
no_pop_no_spam
HomeFAQsBooksHelpWantedsForum letter 36214
Serious Education ... plus the most fun you can have in metal finishing.

Composition of cold blackening solutions for steel, iron, ferrous metal



A discussion started in 1995 and continuing through 2017 . . .

(1995)

Q. I am interested in locating any available information on blackening processes for steel, stainless and brass. My preference would be for a cold process. Any help would be greatly appreciated!

D Vanek


Birchwood-Casey Gun Bluing

(1995)

A. Hi, D. Room-temperature blackening is do-able but more expensive and overall a less satisfactory finish than hot black oxide. We have a quick FAQ intro to cold blackening on line. The Metal Finishing Guidebook has a chapter with formulas for solutions for blackening and coloring metals. But better results will usually be obtained with proprietary blackening systems available from the suppliers listed in our directory or in the yellow pages.

For hobbyist level work, Gun Blue is readily available. Good luck!

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



(1996)

Q. Want cold black coloring process for D2 steel?

Acid resistant, scratch resistant, hard enough . . .

Sayid Budiseno


(1996)

A. Hello, Sayid.

There are room temperature blackening solutions offered by EPI (Electrochemical Products Inc.) [a finishing.com supporting advertiser], Heatbath [a finishing.com supporting advertiser] and others. We have a brief intro about Hot Black Oxide vs. Cold Blackening on line here, and you'll finder deeper coverage in the Metal Finishing Guidebook.

But I think if you are looking for a hard, acid resistant, scratch resistant, finish you may need to think in terms of black nickel, or some other process significantly more complex than a room temperature blackening dip. Good luck!

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



To minimize searching and offer multiple viewpoints, we combined multiple threads into the dialog you're viewing. Please forgive any resultant repetition.



(2001)

Q. I want to blacken iron at room temperature. Is there any way to do it? Also, what is the chemical to be used? I would be interested in making my own rather than buying it.

Rajiv Vyas
- Hyderabad, Andhra Pradesh, India


(2001)

A. Hi, Mr. Yvas. Sorry that I don't know, and will have to answer the same way I answer many people from outside the U.S.A. Basically, people here very rarely "make their own" metal finishing chemicals anymore, so you'll find little about it in our journals anymore; most of the people who know the formulations are employed by the suppliers and obligated to not reveal the formulations.

However, at least some room temperature blackening solutions are selenium and copper based, and you may find general formulation ideas in the journals and technical conference proceedings of 20 to 30 years ago if you do a literature search of that period.

Personally, I find the very best room temperature blackening, developed over a period of decades, to not even be in the same class as hot black oxides. So I think your chances of developing your own satisfactory room temperature blackening chemistry might be slim. Good luck.

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


(2003)

A. Cold black for iron:
tannic acid .......20 gm
tartaric acid......20 gm
water..............1 lit

Cold black II:
coper sulphate.......100 gm
selenic acid..........45 gm
nitric acid...........50 gm
water.................1 lit

Goran Budija
- Zagreb,Croatia



To minimize searching and offer multiple viewpoints, we combined multiple threads into the dialog you're viewing. Please forgive any resultant repetition.



(2002)

Q. Dear sir,

I want to blacken the mild steel sheets I mean to give them a black colour with copper and selenium based material at room temperature, please guide me in this regard. I want to do it for corrosion prevention as well as to beautify the material.

MUHAMMAD NADEEM
- Islamabad, Pakistan


(2002)

A. We have an FAQ about Black Oxide and Cold Blackening, Muhammad. The Metal Finishing Guidebook includes a very good treatment of this subject. Missing will be the exact formulations of modern cold blackening solutions, however, as this is the proprietary knowledge of the companies who have invested in the experimentation. Cold blackening offers no corrosion resistance, although a wax or oil you may finish it off with will help a little.

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



(2005)

Q. Dear reader

We are a manufacturer of finishing products in India. Would like get help on :
1. Composition of cold blackening solution of Ferrous metal.
2. Process

Regards,

Suraj Goyal
chemicals - Mumbai, India


(2005)

A. We have an FAQ about Black Oxide on line here as a quick intro. After that, you could consult the Metal Finishing Guidebook. Then do a lit search and expired patent search. Best of luck with it.

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


(2005)

A. Dear Suraj!
You can use next solution:

6 gms selenic acid
10 gms copper sulphate
4-6 ml nitric acid(1,34 gm/cm3)
1 lit water
20-25 °C temp.
according to Detnner/Elze: Handbuch der Galvanotecnik,1966.

Goran Budija
- Zagreb, Croatia


January 28, 2012

Q. I shall be highly thankful if someone could be given me a guideline for the following: I want to know which compound is used as a surface conditioner / surface activation before Room temperature cold blackening process. It activates the iron surfaces and promotes the formation of uniform, dense and black coating.

Rajkumar Shah
Metal Treatment Chemicals - SURAT, Gujarat State, INDIA



Analytical procedure for Selenium Copper blackening solution?

February 22, 2017

Q. I'm looking for analytical procedures to test Se/Cu based darkening solutions. I have some ideas but some guidance would be most welcome. Birchwood Casey offers a 'send us a sample' but they are not specific about what they do. I like to do it myself.

I have an inclination towards ORP measurements; also, total acidity and pH.

Please help.

dave wichern
Dave Wichern
Consultant - The Bronx, New York


February 25, 2017

Q. Hi Sir,

I have the same problem in composition of Se in cold method for darkening copper.

Can anyone help me about detection of selenium?

Asmaa el-sayed
Chemical Engineer - Alexandria, Egypt


March 15, 2017

A. I think the reactions are as follows:

1) SeO2 2- + 6H+ + 2Zn(s) >> Se2- + 3H2O + 2Zn2+

2) 2Cu2+ + Zn(s) >> 2Cu+ + Zn2+

3) 2Cu+ + Se2- >> Cu2Se

Looks balanced to me. This would make the reaction sharply dependent on H+ conc. and the Zn content of the brass.

There is a colorimetric method for Se based on 1, 4 diaminobenzidine, which sounds, and is, carcinogenic. But it's SeO32-, not total Se that's important.

dave wichern
Dave Wichern
Consultant - The Bronx, New York

ADD a Q or A to THIS thread START a NEW THREADView This Week's HOT TOPICS

Disclaimer: It is not possible to 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; some names may be fictitious and some recommendations may be deliberately harmful.

  If you need a product/service, please check these Directories:

JobshopsCapital Equip. & Install'nChemicals & Consumables Consult'g, Train'g, SoftwareEnvironmental ComplianceTesting Svcs. & Devices


©1995-2017 finishing.com     -    Privacy Policy
How Google uses data when you visit this site.