how to tell a galvanised spoke from stainless

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

Postby pwa » 27 Mar 2020, 10:44am

I have done a lot of work with galv steel but to be honest I'm not sure I could tell whether a piece of steel is galved or not. New galv can be very bright, perhaps almost a bit whiter than steel if that makes sense. It goes dull and grey after prolonged exposure to the elements. On large pieces it can also have globules from the process.

thatsnotmyname
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Re: how to tell a galvanised spoke from stainless

Postby thatsnotmyname » 27 Mar 2020, 10:47am

alexnharvey wrote:I have told you that i have held them beside various stainless spokes and they are different. I think you are contrary and I have little interest in your opinion because you would argue black is white!


Sorry for not telling you what you want to hear. Do you get the difference between 'polished' and 'unpolished' stainless? Doesn't sound like it.

alexnharvey
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Re: how to tell a galvanised spoke from stainless

Postby alexnharvey » 27 Mar 2020, 10:55am

Well, these are old spokes.

I didn't think a picture would be helpful and indeed it hasn't been.

IME there is a quite distinct difference in hue between galvanised items and stainless steel ones. Zinc has a bluish hue. Your eyes may vary.

I do get the difference between polished and unpolished. In fact been there and turned the former into the latter many times over and really don't need your help with that. What I asked for is a test to confirm something that is quite easy to see but clearly is difficult to convey in words or even pictures for some people. Any ideas on that?
Last edited by alexnharvey on 27 Mar 2020, 10:57am, edited 1 time in total.

pwa
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Re: how to tell a galvanised spoke from stainless

Postby pwa » 27 Mar 2020, 10:56am

Galv can have patches of different shade. Hard to see on something as narrow as a spoke, perhaps, but definitely tell-tale if you can. If the finish is uniform I'd suspect stainless rather than galv.

thatsnotmyname
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Re: how to tell a galvanised spoke from stainless

Postby thatsnotmyname » 27 Mar 2020, 10:59am

alexnharvey wrote:Well, these are old spokes.

I didn't think a picture would be helpful and indeed it hasn't been.

IME there is a quite distinct difference in hue between galvanised items and stainless steel ones. Zinc has a bluish hue. Your eyes may vary.

I do get the difference between polished and unpolished. In fact been there and turned the former into the latter many times over.


How do you know they are 'old' spokes?

If you have a bench polisher, try polishing one. If it goes bright, it's stainless.

alexnharvey
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Re: how to tell a galvanised spoke from stainless

Postby alexnharvey » 27 Mar 2020, 11:12am

Which is the odd one out? (Cue tnmn saying three are polished and one isn't)

2020-03-27 11.12.25.jpg

thatsnotmyname
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Re: how to tell a galvanised spoke from stainless

Postby thatsnotmyname » 27 Mar 2020, 11:19am

You said it. We're getting nowhere here. You seem convinced they're galvanised, so good luck with that. Meanwhile, I'll just leave this link here:

https://www.central-wheel.co.uk/product ... e_make=610

Unpolished stainless steel spokes resemble galvanized spokes with the added benefit of being corrosion resistant.

Polished stainless steel gives spokes a chrome-like appearance, but without the same level of maintenance.

alexnharvey
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Re: how to tell a galvanised spoke from stainless

Postby alexnharvey » 27 Mar 2020, 11:26am

So which one differed?

thatsnotmyname
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Joined: 23 Jan 2020, 10:23am

Re: how to tell a galvanised spoke from stainless

Postby thatsnotmyname » 27 Mar 2020, 11:28am

alexnharvey wrote:So which one differed?


From the pic, no3 appears the least shiny from the limitations of my laptop screen, but I'm not sure what point you are trying to make?

Brucey
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Re: how to tell a galvanised spoke from stainless

Postby Brucey » 27 Mar 2020, 11:29am

stainless steel spokes can vary slightly in colour because the steel composition can vary. A few stainless spokes are made of a ferritic grade of steel (and look closer to the colour of chrome plate) but most are made from a composition that is close to 18-8 and have that distinctive slightly yellowy colour.

The colour is a big clue to stainlessness, and it does not vary with the state of polish. The colour originates because there is a band gap in the electronic structure of Nickel which means that when illuminated with polychromatic light the reflections are slightly yellow in tint. If you have ever seen Nickel plate then you know the colour, but 8 percent Ni is enough for most people to be able to see the colour difference between 18-8 stainless and steel with no Nickel content. [However when the lighting has got a strange colour tint to it, the eye usually adjusts so you don't notice, but it does affect your ability to distinguish colours; tinted lighting includes nearly all forms of artificial light and even certain kinds of daylight e.g. near sunset.]

FWIW all stainless spokes are polished during manufacture, but the extent of the polishing varies. In most spokes if you look under a microscope you can usually still see remnants of the 'pickled finish' that is on the wire that they start with.

There are other clues;

- ferromagnetism. A magnet will stick hard to plated steel spokes, but will only be weakly attracted to most stainless spokes. Unfortunately this is a good test for 18-8 stainless spokes (which usually have a ferrite content around 5% or so) but it is not an infallible test for stainlessness, because ferritic stainless spokes are also ferromagnetic in a way that is almost indistinguishable from plated spokes.

- corrosion; galvanised spokes will (obviously) corrode and stain easily. Using some kind of weak chemicals on galvanised spokes will stain them quite easily.

- galvanic potential; by connecting the subject material to a 'control material' in the presence of a suitable electrolyte, you may be able to measure a voltage potential difference, indicating that the control material is different to the test material.

- taste. This might sound mad but you will be able to taste the difference between a plated spoke and a stainless one, if both are clean (oil free).

The colour of galvanised spokes themselves is arguably almost meaningless, because plating conditions can be varied to produce a wide variety of colours. Polishing galvanised spokes can make them look shiny but they are usually slightly more matte than stainless spokes, which often come out of the box with a very thin film of oil on.

FWIW in your (first) photo they look like plated spokes to me. They can be sold as 'rustless' but not as 'stainless steel'.

cheers
Last edited by Brucey on 27 Mar 2020, 11:33am, edited 2 times in total.
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pwa
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Re: how to tell a galvanised spoke from stainless

Postby pwa » 27 Mar 2020, 11:29am

alexnharvey wrote:So which one differed?

I couldn't tell from that pic if they are all galv, all stainless, or a mix.

thatsnotmyname
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Re: how to tell a galvanised spoke from stainless

Postby thatsnotmyname » 27 Mar 2020, 11:38am

pwa wrote:
alexnharvey wrote:So which one differed?

I couldn't tell from that pic if they are all galv, all stainless, or a mix.


Likewise, although I'd still point at no3 as the most different in terms of appearance.

Meanwhile, 'unpolished' is a perfectly acceptable term to use in relation to the surface finish regardless of the science lesson above..

alexnharvey
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Re: how to tell a galvanised spoke from stainless

Postby alexnharvey » 27 Mar 2020, 11:53am

Well, there's a dt stainless, sapim stainless, an unbranded stainless and the unknown one.

thatsnotmyname
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Re: how to tell a galvanised spoke from stainless

Postby thatsnotmyname » 27 Mar 2020, 11:56am

alexnharvey wrote:Well, there's a dt stainless, sapim stainless, an unbranded stainless and the unknown one.


And your point is?

WOT
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Re: how to tell a galvanised spoke from stainless

Postby WOT » 27 Mar 2020, 12:00pm

XRF Analyser would settle it.