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"Touch up anodize with Alodine/Iridite/Chem-film/Chromate?"

FAQs & TUTORIAL:
(to provide context, hopefully helping readers more quickly understand the Q&A's)

Anodizing is an electrochemical process which is performed on aluminum for many purposes including corrosion resistance, hardness, wear resistance, electrical insulation, so that it can be easily dyed for appearance, and other reasons. Please see our FAQ "Intro to Anodizing".

Anodizing can leave small areas under contact clamps, etc. with no or improper anodizing or dyeing, and it is usually impractical to 'spot anodize' those areas to correct the issue. Therefore, many anodizing specifications, including MIL-PRF-8625, will allow a certain amount of 'touch up' of those and similar areas with a chromate conversion coating. "Alodine" and "Iridite" are trade names of product lines of chromate conversion coating chemistry, and "Chem-film" is a synonym sometimes used in the USA. You can search the site for numerous threads about "chromate conversion coatings for aluminum" and "aluminum anodizing".

Current question:

May 16, 2021 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Can Anodized parts be touched up? If so is it the same process as chem film?

Richard De Los Reyes
- Felton ca
^


May 2021

A. Hi Richard. Yes, please see the earlier entries on this thread.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Aloha -- an idea worth spreading
finishing.com - Pine Beach, New Jersey
^


August 14, 2021

thumbs up sign WANTED TO GIVE A HEADS UP THAT AS OF NOV. 23, 2020
MIL-A-8625 HAS BEEN CHANGED TO MIL-PRF-8625.

Philip J. Verzal
Saporito Finishing Co.
supporting advertiser
Cicero, IL

saporito
^




Closely related historical postings, oldest first:

2007

Q. I am looking for a simple touch-up Material, Process, etc., compatible with the black anodize per Mil-A-8625, Type III, Class 2, Dyed Black.

Boris Bayevsky
Mechanical Engineer (Not finishing industry) - Tallahassee, Florida, USA
^


2007

A. Mil-A-8625 F allows touch-up with Alodine.
"3.3.4 Touch UP (mechanical damage and contact marks). Unless otherwise specified (see 6.2), mechanically damaged areas from which the anodic coating has been removed without damage to the part may be touched up using chemical conversion materials approved on QPL-81706 for Class 1A coatings and the applicable method of application. Touch up shall apply only to inadvertent mechanical damage such as scratch marks. For Type III coatings, touch UP shall only be allowed in areas which will not be subjected to abrasion (see 6.1.1). The mechanically damaged area(s) shall not exceed 5 percent of the total anodized area of the item or touch up shall not be permitted. When specified in the contract or purchase order (see 6.2), contact marks shall be touched up using the above method required for mechanical damage."

Christopher D. Arfman
- Seattle, Washington
^


2007

A. Christopher is right for specification requirement. Check with your customer to see if this will be acceptable as to any appearance issues. I had second-tier anodizer (aerospace) ship parts where pits on black anodize filled in with black felt-tip marker. I was "not happy".

Douglas Hahn
aerospace - Saint Charles, Missouri
^



Looking for some way to touch-up Olive Drab Green Anodize?

2007

Q. I need to find a way to touch up Anodized Aluminum parts with a Olive Drab Green Colored finish. Mil-A-8625 [link is to free spec spec at Defense Logistics Agency, dla.mil] Type II or III, Class 2 dyed Olive Drab? Is there a technique or a way without stripping and re-anodizing?

James Black
Product Designer - La Mirada, California, USA
^


simultaneous 2007

A. You can use chromating solutions on bare surfaces and if you add NaF in the solution you can better activity on the surface

Shapour Abd Sharif Abadi
- Tehran, Iran
^


2007

A. Good luck finding one! Actually the timing of this inquiry is quite interesting as I have on my desk a Winsor & Newton olive green acrylic paint, a Zig "Painty" paint maker in guacamole color and a fine point olive Sharpie marker for this very purpose. All resulted in some degree of mismatch that neither myself or our customer (or their customer: US Army) would buy off. My suggestion would be go to a good art store, where the art students shop, and purchase a myriad of marker, inks, paints and such. Again, there is no magic pen BUT if you come up with one, please let me know. My firm and the US Army would greatly appreciate it!

milt stevenson jr.
Milt Stevenson, Jr.
Anoplate Corporation
supporting advertiser 
Syracuse, New York

Anoplate banner
^



To minimize search efforts and to offer multiple viewpoints, we combined previously separate threads onto this page. Please forgive any resultant repetition, failures of chronological order, or what may look like readers disrespecting previous responses -- those other responses may not have been on the page at the time :-)



Is touch-up allowed in Mil-A-8625?

September 29, 2010

Q. Does the mil-spec allow "touch-up" rack marks, scratches, Masking mistakes with paint?

Andrew WITMER
BUYER - Lancaster, Pennsylvania, USA
^


October 18, 2010

A. Yes, unless otherwise specified. Mil-A-8625 [link is to free spec spec at Defense Logistics Agency, dla.mil] F states that,

"3.3.4 Touch up ( mechanical damage and contact marks ). Unless otherwise specified, mechanical damage areas from which the anodic coating has been removed without damage to the part may be touched up using chemical conversion material approved by QPL-81706 [affil. link to spec at Techstreet] for class 1A coatings and the applicable method of application.Touch up shall apply only to inadvertent mechanical damage such as scratch marks. For type III coatings, touch up shall only be allowed in areas which will not subjected to abrasion. The mechanical damage areas shall not exceed 5% of the total anodized area of the item or touch up shall not be permitted. When specified in the contract or purchase order, contact marks shall be touched up using the above method required for mechanical damage."

SK Cheah
- Penang, Malaysia
^



To minimize search efforts and to offer multiple viewpoints, we combined previously separate threads onto this page. Please forgive any resultant repetition, failures of chronological order, or what may look like readers disrespecting previous responses -- those other responses may not have been on the page at the time :-)



Conversion Coating Allowed For Rework of Anodized Parts?

June 6, 2014

Q. Hello. I am a Quality Engineer for an aerospace company and much of our product base consists of aluminum alloy components that are Sulfuric anodized per Mil-A-8625. The question has just been raised about the acceptability of applying a chemical conversion coating (such as Alodine 1201 [linked by editor to info/product on Amazon] or 1132) following rework of an anodized part. For example, if we have an anodized component at Rev B that is subsequently reworked to a new Rev C (we'll assume that a chamfer is added along an edge), is it permissible per Mil-A-8625 to apply a conversion coating to the newly machined surface? Mil-8625, paragraph 3.3.4, says in part "Touch up shall apply only to inadvertent mechanical damage such as scratch marks". Our rework certainly does not fall into the category of "inadvertent damage", and thus the reason for our question. Should this statement be taken at true face value, is there some general industry practice, or is my interpretation of this statement incorrect or too strictly interpreted?

Thanks to all for your input.

Mike

Mike Miller
Sr. Quality Engineer - Goldsboro, North Carolina
^


June 11, 2014

A. Hi Mike,

To me your interpretation is correct, but there is nothing to stop you having some sort of repair/update drawing that could show machining where required followed by chromate conversion coating in accordance with MIL-DTL-5541.

If these are your company design authority you have the right to do what you wish, if you are not the design authority then you need to ask the design authority for permission to carry out the operation.

Brian Terry
Aerospace - Yeovil, Somerset, UK
^


June 11, 2014

thumbs up signHi Brian. Thanks for the feedback. We are the design authority for these parts and I suppose that we could address this practice procedurally, without a need to revise the actual part drawings. Perhaps that is the course to take. We have just always used the CCC on minor rework areas, avoiding the need to strip and re-anodize. Then the question was posed, and we started scratching our heads, realizing that our practice didn't appear to be fully compliant with the wording of the spec.

Thanks,
Mike

Mike Miller [returning]
Sr. Quality Engineer - Goldsboro, North Carolina
^



November 6, 2018

Q. I found the same reference in Mil-A-8625 [link is to free spec spec at Defense Logistics Agency, dla.mil] to use alodine as touch-up for hard anodize. The issue, of course, is appearance. Is there any reason why it would not be acceptable to use black paint or even marker over the alodine touch-up to make the appearance more uniform?

Yossi David
Rugged computers - Herzliya, Israel
^



January 20, 2020 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. can type IIB class 2 anodize be touched up with Alodine? If so, what document would allow it? Anodized per MIL-A-8625.

Fouzi Diab
- Fort Collins, Colorado USA
^


January 2020

A. Hi Fouzi. As you can see from the thread we added your inquiry to, yes, touch-up is allowed under the terms listed in section 3.3.4 of MIL-A-8625 itself.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Aloha -- an idea worth spreading
finishing.com - Pine Beach, New Jersey
^


August 18, 2021

Q. Fouzi, I have the same question about Type II. I see that 3.3.4 talks about Type I & III, but not II. Did you find any additional information?

Ryan
- Lincoln [Nebraska]
^


August 2021

A. Hi Ryan.

sidebar Last name / surname / family name please. This is a site dependent upon camaraderie & aloha, and we have dozens of Ryans, and don't know which one you are or if you're an additional Ryan. Thanks.

I do not read that section of that document as applying only to Type I & III.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Aloha -- an idea worth spreading
finishing.com - Pine Beach, New Jersey
^

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