plating, anodizing, & finishing Q&As since 1989
Color range for Mil-A-8625F Satin Clear Ty II Class I
On parts I am supplying to a customer I have an anodize requirement of MIL-A-8625 / MIL-PRF-8625 [affil link or DLA] F Ty II Class I Satin Clear.
I am using about 5 different anodize supplier and I am getting color ranges from bright metallic, soft metallic, battleship grey, dull gold to a brownish gold. What is correct?
What specification will tell me what is correct as I do not believe it is in Mil-A-8625F, If it is there I do not understand. Will you please help.Margaret Jeanne Rangel
- City of Industry, California, USA
Color matching is often a problem, and the spec you are going by will not resolve the color problem by itself.
I would suspect that the dull gold and brownish gold coatings are the result of dichromate sealing, which is permitted and is a good seal. You can get closer to uniform appearance by either specifying or ruling out the dichromate seal, rather than leaving it an open question.
Probably the best way around your problem is with a "sample board" that shows the limits of acceptable variations and some examples of unacceptable finishes.
Five vendors is probably too many if I may offer unsolicited advice.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Thank You for the answer to my question and if I understood correctly all of the color ranges are acceptable & it is me that has to define what I want the cometic appearance to look like.
Also I started out with one supplier - and progressed to the five - as the situation kept getting worse.
I think I have now narrowed it down to one supplier but as a "Bright Dip" but my customer still wants satin.
Could I get the satin appearance by stating Mil-A-8625 ty II CL I Satin without the dichromate seal?Margaret Rangel
metal forming - City of Industry, California, USA
Calling out satin anodize, even to MIL-A-8625, assures you nothing consistent as far as appearance. One anodizer may choose to "satin" using a mechanical treatment such as glass beading, while another might hot caustic etch, while a third will use a proprietary warm acid etch. All will create a different look once anodized. Sealing in nickel acetate, sodium dichromate, dilute dichromate, low temp fluoride, or boiling deionized water will also contribute to inconsistent appearance. Any or all of these are permitted per MIL-A-8625 as long as the corrosion resistance requirements are met.
You need to create visual standards and distribute them. Next, find the best look and create a standard process for creating the desired look. You'll not likely find it in any book or spec.
Lastly, five is way too many! Anodically speaking, good luck!
Milt Stevenson, Jr.
Syracuse, New York
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