Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ

What is black chrome plating?

Current question and answers:

Q. Hello Sir,

I am from India...

I have aluminium nickel-chrome plating plants...

I want to install black chrome plating plant for my hardware products like door cabinet handles. Can you guide me something please?

⇩ Related postings, oldest first ⇩

Q. What is black chrome exactly? How are its properties different from that of standard decorative chrome plating?

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"Solar power Your Home"

on AbeBooks

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(affil links)

2001

A. Hello WY. You'll find that black chrome plating is a series of finishes that range from looking almost like normal chrome plating with a smoky haze, all the way to a deep almost lamp black color. The smoky chromes are very similar to bright chrome in all particulars and are highly decorative. I don't know all of the characteristics of the very black chromes, but they are used for optical purposes like absorbing reflections in microscopes.

But be aware also of "chrome-look" paint, which is available with a black translucent tint over it, which some people call "black chrome" although it actually just highly reflective paint and has nothing to do with chrome :-)
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

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A. Sir:

The proprietary black chrome baths that were on the market years ago, ran with no free sulphate, but had other additives to form a bit of trivalent chrome. I do recall that years ago, DuPont had a "BK" bath that operated in just this fashion.

When plated correctly (and this could be tricky), the deposit was a rich black color. The operator had to constantly monitor to assure that no sulphate got in, as drag-in from the nickel tank.

Anodes were lead, and the bath did have to be dummied. As a suggestion, I would trace the path from DuPont to the firm that bought out the system. It is a large worldwide firm. They may be able to help you in Hong Kong.

Ed Budman [dec]
- Pennsylvania
With deep sadness we advise that our good friend Ed passed away Nov. 24, 2018
2001

A. Ed is quite correct. I have had some clients who used a process from McGean Rohco (now part of Atotech). I believe this may have been one of the products which were acquired by Rohco from Dupont. With reasonable control, when plated over nickel, dark black deposits were the norm.

Hope this helps.

Gene Packman
process supplier - Great Neck, New York
2001

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A. Black chromium is used for decorative applications and mainly for solar energy applications. It absorbs energy but does not emit it like a black paint. You check the parts by two parameters, absorbance and emittance.

The process is sold by the big suppliers and it is not as difficult to maintain as people mentioned in previous replies. If you work according to specs it works fine.

Sara Michaeli
Tel-Aviv-Yafo, Israel
2001

Multiple threads merged: please forgive chronology errors :-)

Q. I need to find out more information on black chrome plating and black nickel baths. Does anyone have any suggestions on literature that could help me. Also, I have heard nothing but headaches coming from a black chrome bath. Is it possible to achieve consistent results from a black chrome bath on a wide variety of substrate materials with greatly varying Lcd areas.

Thanks in advance.

A. I would not define black chromium as a trouble maker, yet you have to control it and provide what is called a good "housekeeping" in order to ensure constant results. First of all, solution has to be cooled, then make sure that all the chemical parameters are within spec. The anode hooks have to be clean in order to provide good contact. Now let us get to the main question, why black chromium? In case that you need it for decorative purposes and not for solar energy, please consider other blackening solutions that do not involve 400 g/l chromium trioxide.

Sara Michaeli
Tel-Aviv-Yafo, Israel
2001

Q. Well in fact all we do is decorative plating and I am looking for a very black finish that is electroplated on top of nickel and copper. I am currently using an electroblack that is cyanide based. This is giving me a good color but I need the color to be as black as possible with very good wear resistance. This is why I am inquiring about black nickel and black chrome. If there are any suggestions I would appreciate it. Thanks in advance.

A. Black nickel is definitely the easier process to run and maintain, however black nickel is not black. it is a very attractive charcoal grey. The biggest problem we find with black chrome, other then the fact that cooling is most important, is that after a while it no longer plates black which we think comes from nickel contamination, which is very difficult to rectify.

All the best,

Trudy Kastner
electroplating service - Durban, KZN, South Africa
2001

Converting a chrome plated surface to black chrome

The other day in class we were discussing plating techniques. I asked the professor if it was possible to take a chrome plated part and convert it to a black chromed piece by means of chemical conversion. He did not know. I know back in the 60's black chroming was very popular but was later banned due to the process using cyanide. I have a term paper due in a few weeks and it will cover anodizing. But for personal knowledge I am curious in black chroming as well.

Thank you for your time.

Neither chrome plating nor cyanide has been banned in the USA although it is probably true that on a few occasions they have suffered de facto bans in particular locales via the city fathers making operation of such processes too onerous to be worthwhile pursuing.

While environmental pressures against chrome plating do exist, two other things are probably more important in accounting for the drop-off in popularity of black chromium. First, interest in solar heating has declined as photovoltaics have been a much bigger interest, and black chromium was perhaps the best coating for solar collectors. Second, styles changes, and chrome & glass tables are out of fashion.

To my knowledge, black chrome plating is not a conversion coating and does not involve cyanide. Rather the black color evolves during the chrome plating if you operate the bath sulphate-free and use the proper proprietary additives. I don't know the basis of these proprietary additives myself but one thread on this site reported black chrome being achieved with high concentration chromic acid and acetic acid ⇦this on eBay or Amazon [affil links] as the additive.

Setting up a plant for black chrome plating

We intend to set up a black chrome plating plant. Please advise us on how to do it? What are the chemicals required?

Kindly advise us also on what is satin chrome plating and how to go about doing it.

A. Hi Parvez. You and other readers may be interested in listening to our podcast interview with Willie World of Highland Plating about black chrome plating.

There are several ways to do what someone might call 'satin chrome'; perhaps the most basic and common way is to glass bead blast the surface before plating.

Please review our FAQ, "Understanding Chrome Plating", and then get back to us with your specific questions, although it should be noted that you'll probably want to hire a plating consultant to plan the plating plant for you because this is something you design rather than buy from a catalog. Good luck.

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

Are there any disadvantages to having my motorcycle's gas tank and fenders sent off to have them black chromed or onyx chromed. I checked with the owner of the co. and this is a true chroming process?
Is this black chrome more durable than the stock black paint and is it as hard as bright chrome?

It is chrome plating so it's just as hard as chrome (for your purposes; there may be some marginal difference in an engineering situation). Send a picture when it's done :-)

Q. Hi All, I'm facing some technical issues with black chrome plating, the black color can't evenly cover onto the part surface, it look like deeper color tones. Please advise.
Thank you.

Multiple threads merged: please forgive chronology errors :-)

Does Black Chrome have a specification?

Q. Does Black Chrome have a specification? I am very interested in learning more about black oxide and wondered if the plating process was controlled by a specification such as a MIL STD or an ASTM or an AMS can you confirm this.

Multiple threads merged: please forgive chronology errors :-)

Q. Hello, I work for the kitchen appliance industry and one of our teams is interested in products with a BLACK CHROME finish. There are currently in the market products with this finishing (www1.macys.com/catalog/product/index.ognc?ID=225184&CategoryID=30502). I would like to know if the black chrome is the result of a chrome plating process or painting/coating process.

I would appreciate if someone out there can explain me the process to obtain this finishing.

Thank you

A. Hi, Juan. Although it is possible to apply "chrome-look paint" in this general color tone, via a layer of very tiny aluminum flakes or a mirror-silvering process followed by a translucent gray topcoat, real black chrome is an electroplating process. It is very similar to conventional nickel-chrome plating (see our "Introduction to Chrome Plating") except that special contaminants are added to the chrome plating tank to make the deposit this smoked-glass color. Please listen to our podcast interview with Willie World on the subject.

Regards,

Ted,

Thank you for your answer , I already located a supplier that black chromes parts, however they mentioned the parts only withstand up to 150 °C before they turn black.

Q. In the instrument on which I'm currently working, we have need for several optically black surfaces. There is a lot of literature out there that claims black chrome plating is a good solar selective surface and therefore would be good for our application. Meanwhile, our products need to be RoHS compliant which means no mercury, cadmium, lead, and, among others, hexavalent chromium. My question is, can trivalent chromium be plated to yield a good solar selective surface?

Need a surface treatment for aluminum that absorbs 808 nm light while reflecting and emitting very little.

February 9, 2013

A. Hi Jon. My understanding is that all black chromium plating should be RoHS compatible because it contains metallic chrome (valence 0), not trivalent or hexavalent chrome.

I know it's all confusing when it's you're not actually doing the plating, and it's just words, but let me summarize with a little chart --

1. Chromate conversion coatings (gel-like coating applied to aluminum and to zinc plating to deter white rust):
  a. Can be performed from baths containing trivalent chromate, and the result is a RoHS-compliant trivalent coating. (Actually, "trivalent chromate" is an oxymoron because "-ate" implies highest valence state, but this oxymoron is widely accepted in the metal finishing industry).
  b. Can be performed from baths containing hexavalent chromate, and the result is a hexavalent coating that is not RoHS compliant.

2. Chrome plating:
  a. Can be performed from baths containing trivalent chrome, and the result is a metallic coating (zero valence).
  b. Can be performed from baths containing hexavalent chrome, and the result is a metallic coating (zero valence).

Regards,

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

Please see also --

• Topic 3606 "Black Chrome Plating explained"