how to tell a galvanised spoke from stainless

General cycling advice ( NOT technical ! )
Brucey
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Re: how to tell a galvanised spoke from stainless

Postby Brucey » 11 Apr 2020, 8:07am

well that is pretty conclusive!

cheers
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thatsnotmyname
Posts: 595
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Re: how to tell a galvanised spoke from stainless

Postby thatsnotmyname » 11 Apr 2020, 8:43am

Seems to conclude that both are indeed stainless. Discolouration is not corrosion...

Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: how to tell a galvanised spoke from stainless

Postby Brucey » 11 Apr 2020, 9:08am

ten days too late with that one....
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thatsnotmyname
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Re: how to tell a galvanised spoke from stainless

Postby thatsnotmyname » 11 Apr 2020, 9:18am

Don’t know what that means brucey. Wasn’t the purpose of the ‘scientific experiment’ to establish whether the fabled ebay spokes were indeed stainless?

alexnharvey
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Joined: 10 Jan 2014, 8:39am

Re: how to tell a galvanised spoke from stainless

Postby alexnharvey » 11 Apr 2020, 9:20am

The experiment continues. I can either leave it as is and wait for rust to break through or attack the surface some more to speed things up. I'm leaning towards the latter. Or I could file the surface of another spoke then add it in.
Last edited by alexnharvey on 11 Apr 2020, 9:31am, edited 1 time in total.

thatsnotmyname
Posts: 595
Joined: 23 Jan 2020, 10:23am

Re: how to tell a galvanised spoke from stainless

Postby thatsnotmyname » 11 Apr 2020, 9:26am

alexnharvey wrote:The experiment continues. I can either leave it as is and wait for rust to break through or attack the surface some more to speed things up. I'm leaning towards the latter. Or I could file the surface of another spoke then add it in.


Drop a galvanised spoke into the pot. You haven’t done that yet...

alexnharvey
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Joined: 10 Jan 2014, 8:39am

Re: how to tell a galvanised spoke from stainless

Postby alexnharvey » 11 Apr 2020, 9:34am

Not sure if you can see it in the photo but it seems like you can see the difference in could between the coating remains and the freshly exposed steel.
IMG_20200411_093204.jpg

alexnharvey
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Joined: 10 Jan 2014, 8:39am

Re: how to tell a galvanised spoke from stainless

Postby alexnharvey » 11 Apr 2020, 10:23am

I don't think I have a known galvanised spoke for comparison as I try not to buy them. I'll have a look in the shed, maybe on an old wheel. I do have a galvanised shelf bracket that could go in.

I'm quite aware that the are a few other points that I haven't controlled for. For example, I didn't abrade the surface of the DT stainless spoke (it's a spare for a wheel I've built). We already know what happens to roughed up stainless in salt water, just like we know what happens to zinc coatings in saltwater. All sorts of things you could do differently if you would like to.

The offer of a few spokes remains open to all of you.

Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: how to tell a galvanised spoke from stainless

Postby Brucey » 11 Apr 2020, 11:31am

That change in appearance of the suspect spoke is identical to the change that occurs in plated spokes after the first few rides in the winter and a few splashes of salty water get onto the spokes. I've seen it a thousand times before.

cheers
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thatsnotmyname
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Re: how to tell a galvanised spoke from stainless

Postby thatsnotmyname » 11 Apr 2020, 11:45am

Brucey wrote:That change in appearance of the suspect spoke is identical to the change that occurs in plated spokes after the first few rides in the winter and a few splashes of salty water get onto the spokes. I've seen it a thousand times before.

cheers


Don't mention 'hot dinners'. Didn't the OP say he'd already removed the coating (assuming there was any to remove) and/or abraded the surface? In which case the above would not apply..

Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: how to tell a galvanised spoke from stainless

Postby Brucey » 11 Apr 2020, 12:13pm

lightly abrading the spoke is highly unlikely to remove all the zinc plating, and because zinc works as a sacrificial anode, there only needs to be some left and the abraded surface will still react in the same way as normal, but without the possibility that some additional coating/contamination might mask the result.

Those are without doubt plated spokes.
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alexnharvey
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Re: how to tell a galvanised spoke from stainless

Postby alexnharvey » 11 Apr 2020, 12:16pm

A virgin spoke is now in the mix too.

Brucey
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Re: how to tell a galvanised spoke from stainless

Postby Brucey » 11 Apr 2020, 12:30pm

just a point which ought to be obvious, just in case it has been overlooked; it is helpful if the spokes don't touch one another when they are immersed in the solution. If there are just two spokes and they touch one another, whichever one is most likely to corrode will probably still corrode, but once there are three, with two touching, there are several possible outcomes.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

alexnharvey
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Joined: 10 Jan 2014, 8:39am

Re: how to tell a galvanised spoke from stainless

Postby alexnharvey » 11 Apr 2020, 12:33pm

Wasn't an issue with two but it is with four spokes (and although it's obvious when you think about it, I hadn't) so...

2020-04-11 12.32.26.jpg

thatsnotmyname
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Re: how to tell a galvanised spoke from stainless

Postby thatsnotmyname » 11 Apr 2020, 12:40pm

Brucey wrote:lightly abrading the spoke is highly unlikely to remove all the zinc plating, and because zinc works as a sacrificial anode, there only needs to be some left and the abraded surface will still react in the same way as normal, but without the possibility that some additional coating/contamination might mask the result.

Those are without doubt plated spokes.


Nobody mentioned 'lightly abrading' - the OP only said he had removed the plating, without indicating the amount of pressure he had applied during the removal process.

In any case, bare metal will begin to rust very quickly in salt water, and significantly faster than if it was just exposed to open air. You would expect a plated spoke to look significantly worse than that after spending time immersed in a salt solution and yet I do not see any sign of rust whatsoever. So I'll just repeat what I said at the outset - it's not plating - it's stainless.