# What kind of plating is this?



## shawn57187 (Jan 10, 2016)

Hi,
What kind of plating is this? It looks like black cad, but I'm not sure.

The parts are from a Schwinn bottom bracket and headset.  

Thanks!


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## shawn57187 (Jan 14, 2016)

Just answering my own question: I believe the coating is zinc phosphate.  Maybe black oxide, but probably zinc phosphate.


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## momo608 (Jan 14, 2016)

shawn57187 said:


> Just answering my own question: I believe the coating is zinc phosphate.  Maybe black oxide, but probably zinc phosphate.




I would have guessed zinc but that is a guess. Who wants guesses when looking for solid information. Zinc is known as a cheap sacrificial plated surface to protect the underlying steel from corrosion. Schwinn in an effort to cut costs must have thought this good enough for barely visible components. On the other hand zinc plated kickstands and seat tube clamps don't look good for long after a polish, polish too much and you're looking at rust fairly quick. It seems Schwinn did finally start chrome plating kickstands and seat tube clamps near the end of Chicago production based on my observations.


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## shawn57187 (Jan 14, 2016)

momo608 said:


> I would have guessed zinc but that is a guess. Who wants guesses when looking for solid information. Zinc is known as a cheap sacrificial plated surface to protect the underlying steel from corrosion. Schwinn in an effort to cut costs must have thought this good enough for barely visible components. On the other hand zinc plated kickstands and seat tube clamps don't look good for long after a polish, polish too much and your looking at rust fairly quick. It seems Schwinn did finally start chrome plating kickstands and seat tube clamps near the end of Chicago production based on my observations.




Just curious, could it also be manganese phosphate? 

This seems more suitable for cones and similar components because of its anti-galling properties.  That said, it might not have been available in the 60s.


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## momo608 (Jan 14, 2016)

shawn57187 said:


> Just curious, could it also be manganese phosphate?
> 
> This seems more suitable for cones and similar components because of its anti-galling properties.  That said, it might not have been available in the 60s.




manganese phosphate is black only as far as I know. In another thread there was some talk of cold bluing. Manganese phosphate is something the home doit yourselfer can do on the stove top at home for a very good rust preventative surface if you like flat black.


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## Metacortex (Jan 14, 2016)

momo608 said:


> It seems Schwinn did finally start chrome plating kickstands and seat tube clamps near the end of Chicago production based on my observations.




In the June 1967 Reporter Schwinn stated that U.S. Defense Department orders for nickel for the Viet Nam war effort forced the Schwinn factory to use cadmium instead of chrome for plating certain parts including seat posts, #7301 seat post clamps and kickstand sprags. The article also stated that Schwinn had been using cad plating for rust prevention on parts for 35 years prior to that point.

From my observations the mid-'67 change from chrome to cad for these parts applied to most of the popular electro-forged models, however fillet-brazed models continued to use chrome plated seat posts, binders and kickstands (sprags) throughout their production. Years later some of these parts reverted back to chrome on certain EF bikes, for example the Continental (and in '74 the Sprint) had continued to use chrome binders (but not posts or kickstands) but then changed back to using chrome posts and kickstands in '76 and later models.


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## momo608 (Jan 15, 2016)

Metacortex said:


> In the June 1967 Reporter Schwinn stated that U.S. Defense Department orders for nickel for the Viet Nam war effort forced the Schwinn factory to use cadmium instead of chrome for plating certain parts including seat posts, #7301 seat post clamps and kickstand sprags. The article also stated that Schwinn had been using cad plating for rust prevention on parts for 35 years prior to that point.
> 
> From my observations the mid-'67 change from chrome to cad for these parts applied to most of the popular electro-forged models, however fillet-brazed models continued to use chrome plated seat posts, binders and kickstands (sprags) throughout their production. Years later some of these parts reverted back to chrome on certain EF bikes, for example the Continental (and in '74 the Sprint) had continued to use chrome binders (but not posts or kickstands) but then changed back to using chrome posts and kickstands in '76 and later models.




Cadnium makes more sense, it is brighter right out of the tank than zinc. I was going to look into this more because I was also curious about this question. I was leaning zinc because on on a mid 70's varsity I have, my freshly polished NOS kickstand and seat clamp turned flat light gray fast. Didn't think cad could do that. The strange thing is I restored several of the electroforged lightweights in a narrow time frame using NOS kickstands on a few of them. All the bikes standing next to each other in the same atmosphere indoors, a lot of the parts in question deteriorated at different rates and appearances. Some looked like I just polished them, others went to hell with actual brown rust. Being inside the house this surprised me, I have other items nearby in bare white steel that show no corrosion at all and they have been sitting there for years. I also found that waxing these parts helped nothing. All this happened over a few month period. Anyway, I pulled the bad parts and had them chrome plated.


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## shawn57187 (Jan 15, 2016)

momo608 said:


> manganese phosphate is black only as far as I know. In another thread there was some talk of cold bluing. Manganese phosphate is something the home doit yourselfer can do on the stove top at home for a very good rust preventative surface if you like flat black.




I believe these pieces should have started out black.  I bought a NOS piece and it was solid black, with a purplish tint. My original photos don't show the blackness well because of the flash and the thinning of the original finish.  Thoughts?


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## momo608 (Jan 15, 2016)

Here is a helpful link I ran across describing different coatings. This doesn't explain everything but I think it addresses this particular interest.

http://429mustangcougarinfo.50megs.com/new_page_26.htm


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