Chrome pitting

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fallguy1000
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Chrome pitting

Post by fallguy1000 » Wed Feb 05, 2020 8:06 pm

I have enough stanchions for an entire catamaran. But they are sorta pitted.

Any ideas?

I think they are cast stainless.

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Aripeka Angler
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Re: Chrome pitting

Post by Aripeka Angler » Wed Feb 05, 2020 8:48 pm

Happich semichrome polish.
Raced dirt bikes as a little kid, best polish we found.

https://www.amazon.com/dp/B004F5BDIO/re ... NrPXRydWU=

edit, won’t remove the pits but I guarantee the metal will look a hell of a lot better...
Richard
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piperdown
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Re: Chrome pitting

Post by piperdown » Thu Feb 06, 2020 11:57 am

Send them out to be stripped and re-chromed?

If it was me though, I'd just sandblast them to remove the old chrome and then run my electroplate system and re-chrome them. Probably use a metal filler "bondo" on the pits to fill them in and them chrome them.
Eric (aka, piperdown)

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Evan_Gatehouse
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Re: Chrome pitting

Post by Evan_Gatehouse » Thu Feb 06, 2020 5:06 pm

Those are pretty ugly pits (I think) from the photos. The odd thing is what looks like chrome plating peeling back from the countersinks??

You're pretty sure they are not zinc with chrome plating? That would be my guess. Scrape the base with a knife. s.s. will be very hard to scrape but zinc, being softer will scratch more easily. Compare with scratching a s.s. bolt for reference.

If you are sure they are s.s. then electropolishing them will help. It removes a thin layer of the base material and will coat the pits a bit.

I've also seen cast aluminum stanchion sockets but they a duller grey finish.

Perko used to make cast bronze with chrome plating but probably haven't made them for decades.
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Evan_Gatehouse
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Re: Chrome pitting

Post by Evan_Gatehouse » Thu Feb 06, 2020 5:10 pm

The chrome plated zinc alloy is known as Zamak

Still sold in places:

https://www.jamestowndistributors.com/u ... ?pid=12677
designer: FB11/GV10,11,13/ HMD18/
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fallguy1000
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Re: Chrome pitting

Post by fallguy1000 » Thu Feb 06, 2020 5:29 pm

Evan_Gatehouse wrote:
Thu Feb 06, 2020 5:10 pm
The chrome plated zinc alloy is known as Zamak

Still sold in places:

https://www.jamestowndistributors.com/u ... ?pid=12677
Yeah. I think so. A form of pop can metal or the pop can metal, right?
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Re: Chrome pitting

Post by terrulian » Thu Feb 06, 2020 5:53 pm

I'd guess it's stainless. It's stainless, not indestructible. If you're doubtful, put a magnet on it. Won't stick to stainless, or extremely weakly depending on the formula. I'd just live with it or put up the cash for new ones.
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Re: Chrome pitting

Post by Aripeka Angler » Thu Feb 06, 2020 7:32 pm

I was replying because it was thought to be stainless. If it’s really plated zamac, I’d throw it in the trash. :wink:
Richard
Completed boats...XF20 "Red Alert", Aripeka Angler's Strip Canoe, FS18 “Bare Bones”, GF12
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Re: Chrome pitting

Post by Capt UB » Fri Feb 07, 2020 11:00 am

If I remember right, my fittings were Bronze with chrome plating. They too pitted a bit, would see a green stain at the pitting. I would just clean (not polish), then light coat of carnauba wax on them.
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Evan_Gatehouse
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Re: Chrome pitting

Post by Evan_Gatehouse » Tue Mar 03, 2020 1:52 am

Zamack is a zinc alloy. The chrome plating protects it for a while, but when it breaks down the zinc part of the alloy gets eaten away.

Like brass is an alloy of copper + zinc. In sea water it gradually "dezincifies", with the zinc going away, leaving a pink spongy copper remainder that is very weak.
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