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OPTICAL BLACK ANODIZE / MARTIN BLACK





An ongoing discussion from 2000 through 2019

2000

RFQ: I am looking for a source for Martin Black. I believe it is an anodizing process that produces a non-reflective surface on aluminum. We are looking to coat the inside of a optical cavity.

David K [last name deleted for privacy by Editor]
- Calgary, AB, Canada

Sorry, this RFQ is outdated, but technical replies are welcome. No public brand/source suggestions please ( huh? why?)


(2000

A. Martin anodize, or Martin Hardcoat or Mod Martin is simply an old proprietary name for an anodize / hardcoat system.

Here, we used to do Mod Martin Hardcoat and anodize, and I still could do it, but there is really nothing special about it. We have learned much more over the 30 - 40 years since Martin systems were developed.

I think you should just be looking for generic black anodizing.

David A. Kraft
- Long Island City, New York




Low Outgasing Black Coating/Plating for Copper or Aluminum

2000

Q. I am looking for a black coating or plating to be applied to sheet aluminum or sheet copper. This plating must be low outgassing, as this is a vacuum application.

In a recent issue of a mechanical design magazine, an article claimed that an optical coating called "martin black" was such a vacuum compatible, low outgassing coating. A web search on "martin black" led to this site. Various letters talked of it's optical qualities. One claimed that is term is a shortening of "Martin Marietta Black", and another claimed that this is just "plain ol' black anodizing". Are "martin black" and black anodizing (black oxide?) all the same? If so,I've been told that black anodize has bad outgassing qualities. Does it?

Any info/insights are greatly appreciated.

Thanks In Advance,

Frank Modica
- Princeton, New Jersey



2000

A. If the application is for heat absorption or reducing reflection, I could suggest a couple of ways. Black anodizing will do as well as black chrome. However, we have also used a vacuum compatible graphite paint. This one is easy to apply repeatedly using a brush and remove by rinsing. I had found the vendor at the SVC conference four years ago. Unfortunately, I have run out of it and I need to find it again. Since I will be attending the conference again next week, I will let you know if I find it again.

Mandar Sunthankar
- Fort Collins, Colorado



2000

Mandar - Did you get the contact? Thanks.

Paul Kochendorfer
MRC - Laguna Hills, California US



2000

Unfortunately Paul, No. I asked several vendors there but no luck.

Mandar Sunthankar
- Fort Collins, Colorado



2000

A. Try Acheson Colloids. They provide a low gas black. Product name is RW9932.

Robert Killion
Central Coating Company - WestBoylston, Massachusetts



2000

A. See US patent 4111762 and related patents.

It is made essentially by shaping the surface (like an anechoic chamber but with much smaller features) and then helping the light trapping with a black finish e.g. black anodization.

Carlos Zarate
St.Catharines, Ontario, Canada




2001

RFQ: Looking for a supplier of "Martin Black" coating (or Martin Marietta Black). It is a coating with very good optical qualities.

Thanks,

John V [last name deleted for privacy by Editor]
- Boston, Massachusetts

Sorry, this RFQ is outdated, but technical replies are welcome. No public brand/source suggestions please ( huh? why?)



To minimize searching & thrashing, multiple threads were merged; please forgive repetition, chronology errors, or disrespect of other responses (they probably weren't there) :-)



2000

Q. I AM A ANODIZER OF 21 YEARS. ONE OF MY CUSTOMERS IS ASKING FOR OPTICAL BLACK ANODIZE. WHAT IS OPTICAL BLACK? I REALIZE THAT IT IS A REFLECTIVE MATTER. CAN YOU HELP ME? THANK YOU.

JIM KLEIN
metal finisher - GRANTS PASS, Oregon USA



2000

A. Hi Jim,

In my assumption, optical black is a non etched surface, black anodized. I have done this before for some people and that's the way they specified it. It might be more detailed than this, such as a bright dip prefinish before the anodize, but they requested it in this fashion. Take it with a grain of salt, I'm just doing my best to spur thoughts and possibly solutions

Matthew Stiltner
plating company - Toledo, Ohio



2000

A. Someone requesting optical black anodize is probably working with optics, such as in some type of camera, telescope, etc. A primary concern in this type of work is stray light, such as might be reflected from a bright shiny surface, and so a black, matte, non-reflective surface on peripheral areas is preferred.

John F. Brewer
- Akron, Ohio



sidebar 2000

Interesting you mention this John. Like I originally stated in my response, this is what was requested of me. I guess its 6 of one and 1/2 dozen of another eh? I guess your response makes more sense to me than the bright finish does, based on your examples. But again, I just play by the rules laid out to me by the customer.

He was using the parts on a high powered telescopic device of some sort. I see advantages myself to using both finishes frankly. The bright glossed surface providing for more reflection and scattering of the lighting, and the non glossed finish for doing the exact opposite.

Matthew Stiltner
plating company - Toledo, Ohio



2000

I suppose you hit it on the head, Matthew: whatever rules the customer lays out for you as Optical Black is what you should provide.

John F. Brewer
- Akron, Ohio


2000

A. I would have to agree with John that typically "optical black" would be non-reflective, as is the case for a customer that I anodize parts for now. However, since you have two good but differing opinions on what "optical black" means, your customer may have be more specific, reflective or not. Good Luck.

Lamar Jackson
- Fort Walton Beach, Florida



2000

A. Optical black means there is an absence of returned light (near zero reflection). If you look inside a camera, all light reflection is suppressed using the optical black coating. This coating is dull. This could be either anodization or black chrome, I do not know. It does not get easily scratched, that I know.

Mandar Sunthankar
- Fort Collins, Colorado



2000

A. Optical black means a minimum of reflection, both specular and non-specular reflection, this means black and as matte as possible. The best results are from a very matte etch or bead blasting and using a good black dye. There is I recall a Martin Marietta optical black process specification which has been used.

Leo Herrington
- Grand Rapids Michigan



sidebar 2000

thumbs up signAlright seeing as how everyone has chimed in on this one. I've tucked this away for future reference, as per what everyone else has stated, optical black will forever remain a matte finish, etched and one that diffuses the light reflection capabilities of the material. And now that Leo's ponied up some thoughts on this (I buy my dyes from him, so I trust his word on this one) it's a done deal as far as I go, I'm convinced you guys had it right, someone else had it wrong, and passed on the misinformation to me and I in turn passed it on here. Thanks for the clarification everyone.

Matthew Stiltner
plating company - Toledo, Ohio



2000

Hi, Matthew. Now that you've apologized for being wrong, I'll chime in on your side and have to apologize too :-)

What is the difference between a matte white surface and a mirror? If chosen correctly, they may have exactly the same reflectivity, but the reflection from the white surface is thoroughly diffused and scattered whereas for the mirror, the angle of incidence equals the angle of reflection so it can form an image, right? Now, by definition, a black surface, whether polished or matte, reflects very little to no light, right? And if no light is reflected, what difference does it make whether the reflection would have been diffuse or not? The concept doesn't even have any meaning: if it's truly black, it's neither specular nor diffuse, it's just black   :-)

But, yes, it will be much easier to achieve a very black surface on a matte profile than a polished one because a portion of the light will bounce from one black spot to another, offering multiple chances for absorbing the light.

Regards,

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


2001

A. Optical Black Anodize, is an electrolytic process and uses an inert metal compound. This coating replaces the conventional organically dyed coatings where thermal stability, UV degradation or reflectivity are an issue. This process can be used only with 6000 or 5000 series aluminum alloys. We use this process for our UV Laser Optics.

Cater D. Carroll
- Portland, Oregon, USA



2001

A. Optical black anodize is a proprietary coating developed by my company in Sherwood Oregon for use by the optical industry where low reflectivity, low outgassing and U.V stability are desirable with the durability of a conventionally anodized surface.

Richard Brehterton
anodizing company - Sherwood, Oregon, USA



2001

If you feel that your company owns the phrase 'Optical Black Anodize', Richard, let us know and we'll be happy to credit it! But I doubt that other anodizing shops will concede that widely-used phrase to you without proof; it seems to be pervasively used in the literature and in patent citations.

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



2003

A. Martin Marietta "Optically Black" anodize is outlined in US patent #4,111,762 (expired) which can be downloaded from the USPTO website.
http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=1&f=G&l=50&co1=AND&d=PTXT&s1=4111762.PN.&OS=PN/4111762&RS=PN/4111762

Michael Lines
- Provo, Utah, USA




To minimize searching & thrashing, multiple threads were merged; please forgive repetition, chronology errors, or disrespect of other responses (they probably weren't there) :-)



Black body coating alternative to Enhanced Martin Black

2002

Q. Hi,

I am a final year student at the university of Hertfordshire and currently working on my project. I am currently looking for a comparable performance/process and cost of a High emissivity coating which is good for space use, i.e. No/low outgassing, resistant to vibration etc... compared to Enhanced Martin Black.

Can anyone help?

Cheers,

Andrew Lewis
University of Hertfordshire - Hemel Hemsptead, Herts, UK



2003

Q. Andrew,
I have nothing new at the moment about black body coatings, but I would like to know if you received other replies or worthwhile suggestions. I will be actively searching for methods to produce such coatings, including physical vapor deposition methods.

John Marshall
- Boulder, Colorado USA




Vacuum Compatible Paint

2003

Q. I am studying the reflectance properties of minerals in ultra high vacuum, with light white and infrared from 25,000-600 cm^-1. I am having problems with stray light bouncing off the wall. I tried to spray down the chamber with a vacuum compatible graphite spray. However, although it is improved, I would like to make the walls even darker. I heard about this Martin Black substance and wanted to know if it was vacuum compatible at say 10^-10 Torr and if I could bake my chamber at like 10^-7 with it in there and if so where I could get it. If Martin Black is not compatible or if you know of something better, please advise me.

Thank you for your time.

Mark Loeffler
University of Virginia - Charlottesville, Virginia, United States



July 6, 2015

A. I don't know if this will work for your application (I have not used it myself):
www.lord.com/products-and-solutions/coatings/aeroglaze-z306-polyurethane-coating

Peter Petit
V-Glass - Pewaukee, Wisconsin, USA




2004

RFQ: Please advice where can I purchase "Martin black" paint or LORD Chemglaze/ aeroglaze? I need it for my optical housing (visible).

Thanks,

Oded Wigderson
Medical imaging - Haifa, Israel

Sorry, this RFQ is outdated, but technical replies are welcome. No public brand/source suggestions please ( huh? why?)


A. Hi, Oded.

We appended your inquiry to a thread that partially answers it, so now you know that Martin Black isn't exactly paint. Letter 1670 addresses the Lord Chemglaze/Aeroglaze question. Good luck.

Regards,

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




Martin Hard Coat Problems

2004

Q. We use a Martian hard coat process for hard anodizing aluminum (sulfuric acid solution saturated with CO2 at 32 °F. Most of the time the color of the oxide is green. Occasionally, we get back coatings. Some of our customers want the black colored coating but we are not able to reproduce the color. Recently we anodized some parts which the customer says are both 6061 aluminum. One group of parts come out green and the others black. Can anyone tell me what can cause the color variation? How can one get black hard coat.

Thank you for your help.

Best regards,

Aysun Scott
Plating Shop - Kansas City, Missouri, USA



2004

A. Any color variation you get in un-dyed hardcoat is directly attributed to the alloy of the aluminum & the thickness of coating.

If two parts are run in the same load and come out different colors they are most likely different alloys.

To get black hardcoat you can dye the parts after hard anodizing & then seal them, just remember, when you dye & seal you lose abrasion resistance.

David A. Kraft
- Long Island City, New York



2004

? Is the material extruded or machined from extruded bar stock?

Chris Jurey, Past-President IHAA
Luke Engineering & Mfg. Co. Inc.
supporting advertiser
Wadsworth, Ohio
luke banner



2004

thumbs up signThank you for your comments. We do not know if the material is machined from extruded bar stock. A lot of times we don't even know what type of aluminum we are getting.

Best Regards.

Aysun Scott [returning]
- Kansas City, Missouri, USA



Hi Aysun. As long as you fully realize that attempting to hard anodize unknown aluminum alloys is a serious problem that must be corrected, and you're working on fixing it ...  :-)

Regards,

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




April 25, 2011

! Detailed description of various optical black coatings - including Martin Black - is at
www.optics.arizona.edu/optomech/papers/persky%201999.pdf

Jim McCann
aerospace - Tucson, Arizona USA


----
Ed. note -- July 2015: Sorry, that link is now broken.

Readers: links almost always have a very short life compared to our pages. If posting a link, please try to include the title of the article, or even an abstract, so people can find it.
Feb. 2016: link is corrected in entry below. Thanks Dan!



4581
February 19, 2016

thumbs up sign Regarding the invalid link to the Persky paper, here is a new link:

http://fp.optics.arizona.edu/optomech/papers/persky%201999.pdf

The title of the paper is "Review of black surfaces for space-borne infrared systems" by M.J. Persky. It was published in Review of Scientific Instruments, Volume 70, number 5, May 1999.

Dan Razum
Q-Value Add - Penang, Malaysia



January 22, 2019

A. I am a retired electrical engineer. I worked for 20 years at Lockheed Martin, and Martin Marietta before they merged with Lockheed. I often worked with optical engineers on spacecraft. They needed better optical black surfaces than simple flat black paint could produce. It had to be as close to zero reflective as possible and it had to be vacuum proof. Also, it had to not degrade with time or light exposure. A coating was developed called Martin Black. Later, a small number of people left Martin and started a company in Boulder where they perfected an even better coating for this purpose. I don't remember further details (see my first statement)

Woody Brison
- Littleton, Colorado, USA


----
Ed. note Feb. 2018: And now that one no longer works. Such are links on the internet :-)
but try this one:
https://wp.optics.arizona.edu/optomech/wp-content/uploads/sites/53/2016/10/persky-1999.pdf none

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