Stripping Black Parts and Burnishing

[lconley]

In general, I do not like black parts on bikes with silver components. What is worse is silver components with black parts (exceptions: 1st generation Campagnolo super record derailleurs and Suntour Cyclone derailleurs, it was all downhill from there). Case in point for the components are polished silver Cromag Scarab pedals with a black dust caps. For the bike example, you cannot buy a long stoker stem for a tandem in any other color than black. I have no black components on my Hubbuhubbuh, the the cool but too short V shaped Nitto stoke stem needed to be replaced. So I got a nice long Control Tech stoker stem and stripped it with Easy-OFF. Same for the visible ends of the Cromag Scarab pedal dust caps. Now silver, but the stem looked terrible. The dust caps were OK, but not up to the standard of the rest of the pedals. Always looking for an excuse to buy a new tool, I bought a Vevor 5 kg tumbler and 4 lbs of additional SS media to burnish the parts. The stoker stem is still tumbling, but here is a comparison of the tumbled and un-tumbled dust caps as well as the head tube cable stops for my Custom (were always silver but not shiny). Nothing earthshaking but i am quite pleased. The burnishing does not give a smooth finish, but shines up whatever is there. Polishing is a lot more work. This is after 1 hour in the tumbler. The burnished versions are on the right.

This are the befores for the stripped stoker stem.

It is still tumbling.

Next - Silver Skeleton Key Front Derailleur or ??

Laing

Delray Beach FL

[lconley]

Burnished:

Much better. May do some more polishing / burnishing later, but good enough for now.

Laing

[Nick Payne]

I wanted a silver NW chainring in 34t for use with silver 110BCD cranks, but could only find them in black. Anyway, I bought a pair of black anodised Hope chainrings in that size, mixed up some caustic soda drain cleaner in a plastic bowl, and gave one of the chainrings a couple of minutes in the solution, using a stainless spoke to turn the chainring over at the half way mark. Don't leave in the solution too long or you will be removing metal rather than just anodising. Rinsed and dried the chainring and gave it a quick scrub with 0000 steel wool. It still looked slightly black because of the reaction between the alloying elements in the 7075 aluminium and the NaOH. The aluminium saucepan cleaning trick got this black off - a couple of tablespoons of white vinegar and cream of tartar in some water in a saucepan, and simmered the chainring for about 15 minutes.

This is the end result - both chainrings were originally black. This process will only work for parts that are anodised black or some other colour, not for parts that have been painted. There, you would have to strip the paint by some other means:

Nick

[Eric Marth]

Looks good, Laing, the tumbler sounds like a nice bit of equipment to have on hand. 

I recently de-anodized and polished four sets of Paul cantilever brakes and a set of Paul levers. Also four Moon Units. Two sets of brakes were clear anodized or "silver" and the other two sets were black anodized. The levers were "silver." 

Before I started the project I called Paul Comp and talked to Paul. He said the first thing you gotta do is remove the anodizing. He mentioned that some people use oven cleaner but that it doesn't work very well. He suggested looking for a local company that could de-anodize the parts for me and that there were likely more around than I might expect. 

I used a de-anodizing solution from Jestco Products. They sell polishing equipment, buffing kits and other stuff for polishing metal. Add one tablespoon of the powder per quart of hot water and soak the parts for 15-20 minutes. I used hot tap water at 120º. Wipe the parts dry then buff on a buffing wheel with white polishing compound or buff by hand with Simichrome (available from Velo Orange). Make sure to wear eye protection and respirator when working around the de-anodizing solution and polishing equipment with high RPMs. 

I used a white buffing wheel mounted to a bench grinder with white mirror finish buffing compound.  

I don't have any before pictures but just imagine black anodized parts and the dull-silver finish. 

[Eric Marth]

I found a not-so-great before picture. 

[Garth]

While I love the idea of changing a black anodized part into a silver one, I've never done it because of those particular kind of chemicals are like insta-nausea to me.  I'd be more apt to sand and paint a part myself. I painted some lugs of my '83 Stumpy with just Testors and a brush and it remarkably remained in tact when I sold it some 10+ years ago.

Do either of you leave the finish raw or do I apply some sort of gloss clear coat ? My experience with raw aluminum hubs is they're great after polishing but it doesn't last long so it's rather a never ending thing if you want it consistently shiny. I ended up just leaving them turning that dull grey. 

[Brian Turner]

I find it curious that many of us seem to own similar self-healing cutting mats. 

On Sep 3, 2022, at 3:31 PM, Garth <gart...@gmail.com> wrote:



While I love the idea of changing a black anodized part into a silver one, I've never done it because of those particular kind of chemicals are like insta-nausea to me.  I'd be more apt to sand and paint a part myself. I painted some lugs of my '83 Stumpy with just Testors and a brush and it remarkably remained in tact when I sold it some 10+ years ago.

Do either of you leave the finish raw or do I apply some sort of gloss clear coat ? My experience with raw aluminum hubs is they're great after polishing but it doesn't last long so it's rather a never ending thing if you want it consistently shiny. I ended up just leaving them turning that dull grey. 

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[Patrick Moore]

The polished crank bolts and derailleur lever stops look very good; please do post a photo of the stem in final form.

Request: Please describe your post-tumbling polishing method.

And question: What model is your Vevor tumbler? I see that prices range from $65.47 to almost $150.

Thanks.

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Patrick Moore

Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum

[Garth]

I found this thread on bikeforums which is part one of three that answered the many questions I had about this. If I did it all outside with a light breeze to blow the odor away I just may be able to do it. There's some photos of a really beat up black ano 3T stem that was made all shiny even though the deeper scratches remained. That's what I'd call more than "good enough" ! 

https://www.bikeforums.net/classic-vintage/715486-drillium-how-guide-part-one-stripping-anodizing-2.html

[Eric Marth]

Here's another helpful article: https://lixbmx.com/de-anodising

[lconley]

It is the 5 kg, 80w version, not the smallest 3 kg, 60 version. The drum on the smaller version was too narrow to fit the long part of the stem. $99.95 less 8%, on sale -> $92.

The tumbler came with 1 lb. steel balls. I bought an additional 4 lbs. of Stainless Steel shapes - balls, pins, trapezoids, flying saucers. If I were to do it over again, I would just get the pins, the balls and flying saucers tend to get caught in holes and crevices. The pins will also be good for polishing brass cable ferrules. Pins are what the ammunition re-loaders use to polish the used brass casings. There seem to be three basic types of tumbler users - jewelry, rocks and gun ammunition re-loaders. You can get much larger tumblers from the ammunition re-loader sites. I did not get the Harbor Freight tumbler because I read in several places that the black tumblers that Harbor Freight uses tend to rub off when using stainless steel media and turn what you are tumbling black.

Post tumbling - rinse with water. I cannot find my tube of Simichrome at the moment.

Laing

[Patrick Moore]

Thanks for the added information. I'm tempted to go out and buy one and start tumbling things, but should doubtless reign in my enthusiasm until a time of real need. I do have a black-anodized seatpost that is scratched in many places that would probably turn out well from this treatment ... a couple of stems or seatposts tumbled from black to silver would cover the investment.

Patrick "I wonder why you need to polish used brass bullet cartridges ...???" Moore, who also has momentary enthusiasms for taking up black powder shooting.

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[lconley]

You cannot fit a normal 250mm seat post in this tumbler drum. That would require a tumbler drum about twice as wide. The longest of the parts of the stem barely fit on a diagonal. The interior width is only 6-1/2 inches (165mm). There are some YouTube videos about people who make larger drums and tumblers at home. Not sure how big you can buy non-commercial tumblers.

Tried stripping some black Shimano bar end pods yesterday. They laughed at the EasyOff. Must be powder coated, or something else, but not anodized.

Laing

On Wednesday, September 7, 2022 at 7:10:26 PM UTC-4 Patrick Moore wrote:

Thanks for the added information. I'm tempted to go out and buy one and start tumbling things, but should doubtless reign in my enthusiasm until a time of real need. I do have a black-anodized seatpost that is scratched in many places that would probably turn out well from this treatment ... a couple of stems or seatposts tumbled from black to silver would cover the investment.

Patrick "I wonder why you need to polish used brass bullet cartridges ...???" Moore, who also has momentary enthusiasms for taking up black powder shooting.

On Mon, Sep 5, 2022 at 9:45 AM lconley <lco...@brph.com> wrote: