Where the
world gathers for metal finishing
Q&As since 1989


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Dow #17 and other finishes on magnesium (bicycle components)

2004

Q. My name is Alan McCorkle and I collect/restore vintage BMX bicycle parts. I am particularly interested in items manufactured by a company called Hutch Hi-Performance Products and Titron Titanium Components. Hutch, owned by Richard Hutchins, was in business from the early 80s until the late 80s and they were located in Pasadena, Maryland (later Baltimore). Hutch made many different bicycle parts including frames/forks, cranks, hubs, pedals, and various other components. They are most well-known for their round beartrap style pedals, use of exotic metals such as titanium and magnesium, and their love of chrome plating. Most of the Hutch components including the pedals and magnesium sealed bearing hubs were designed and manufactured in 1980-81 by a company called Titron Titanium Components in Lemont, PA. Titron was owned by a Mr. Bill Grove who would eventually go to work for Hutch when his company and product designs were purchased by Hutch in 1981.

The component I need help with is the magnesium hub which was made from AZ31B magnesium. The hub is a 3-piece design with the flanges being pressed onto the center of the hub. The hub also used titanium axles and sealed bearings. The hubs were available in several different finishes including: a matte gray finish (which I am told was electroless nickel), chrome plated, black, and a two-tone finish where the hub flanges are nickel plated and the hub center is a semi-gloss black finish that almost looks anodized. I have learned that the coating used under the black finish is most likely Dow #17 (described by Mr. Bill Grove as an ugly green color but he does not recall the entire finishing process since it was outsourced and it was 20+ years ago) but it is the final black finish that remains a bit of a mystery. The inside of the hub center is also the same black finish which seems to suggest that it is not painted or powdercoated and the finish does not chip or flake.

My questions are:
1) What coatings other than powdercoating or paint would have been used over Dow #17 to produce this black finish?
2) Is it a "black" finish or a product that when applied over the Dow #17 creates a black color?
3) Would Dow #17 also be used under the nickel finish?

The nickel plated flanges of the hubs are in fair condition with some pitting where the nickel finish has expired (for lack of better description). Is it possible to repair the pitting in the magnesium prior to refinishing? Can these pits be filled with another material?

I am very interested in learning about all of the different possibilities for restoring these items. Pictures of the hubs are available here:

   

Alan McCorkle
Hobbyist: Vintage bicycle collector - Fairfield, California, USA

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Coating for AZ91 magnesium with excellent corrosion and wear resistance

1996

Q. Looking for a plating for a AZ91 magnesium casting. The plating should be with the following characteristics:

1. Excellent corrosion resistance.
2. Excellent wear resistance
3. Conductive plating (not a must)

Avihu Cohen

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Dow 17 Process Parameters

I am in need of information on the Dow 17 Magnesium Anodize process, i.e., Required current values, operating temperatures, tanks required, etc. All responses would be greatly appreciated.

John Mars
Metal Finishing - Wichita, Kansas, USA
2004

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Boeing Finish code SRF-3.30

Q. Can somebody tell me the specs for Boeing finish code SRF-3.30 ? There is any site where I can find the specs for those finish codes?
I'll greatly appreciate any help

Hermes Rivas
Manufacturer - Miami, Florida, USA
May 30, 2008

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Anodizing magnesium on racks made of aluminum

Q. Sirs,

I tried to anodize magnesium using aluminum racks, this because it's easier to get aluminum racks than magnesium racks but I had not success; does somebody know why you can't use aluminum racks to anodize magnesium parts?

Regards

Yohands Rey
manufacture engineer - Chihuahua, Mexico
January 13, 2011

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Need Shop to do Dow 17 Process

RFQ: Looking for a Southern California based plater who does Dow 17 on Magnesium.

David D [last name deleted for privacy by Editor]
Electronics mfgr. - Irvine, California, USA
2005

Ed. note: Sorry, this RFQ is old & outdated, so contact info is no longer available. However, if you feel that something technical should be said in reply, please post it; no public commercial suggestions please ( huh? why?)