white thing on rim around spoke holes/nipples?

On Sun, 03 Jul 2016 16:38:40 +0200, Emanuel Berg
wrote:

Jeff Liebermann writes:

You can't. Once the base metal has been
corroded (oxidized), the metal is converted
into a salt (ionic compound created by mixing
an acid and a base), which is the white stuff
you're dealing with. The damage has already
been done when the base metal was lost.
Cleaning off the salts (the white stuff) does
not restore the metal to its former
condition. It only removes the salts (the
white stuff).

OK! Salty water, should be pretty easy to
remove! But it wasn't, it was more difficult to
remove than rust! Perhaps got intermingled with
the aluminum and/or coating?

I can't offer any specifics until you provide
some detail as to what was corroded. Was it
the aluminum rim, steel washer, brass spoke
nipple, chrome plating, or stainless
steel spoke?

This is something I've thought about a lot, how
do you determine what is what? I know only
about the non-magnetism test for stainless
steel. (I know the yellowish gold color of
brass, of course.)

And yes, the spokes have washers! Not common,
but yes, now that you say it, those I've seen
have all had this problem! So perhaps the
nipples are not the problem, but the washers
(in combination with the nipples and/or rim)!

On what materials should you, and should you
not, use the hair, nylon, brass, and steel
brushes, sand paper and emery, steel wool
and Svinto?

I never gave this much thought or actually
I did give it some thought and that thought was
I didn't know the answer

Actually the only sure test is to have a lab test the material -
usually by some process that burns the material and views the spectrum
(I think).

In addition there are all kinds of "blacksmith" tricks. You can find
photos showing you how to identify some metals, usually an ferrous
material by grinding it and see what the sparks look like
https://en.wikipedia.org/wiki/Spark_testing
Or pictures at:
https://www.youtube.com/watch?v=7PWCh6fdXdw
You can also spark test titanium :-)

The magnet test simply tests how much ferrous metal (iron) is in the
material. Some stainless', for example, are magnetic, and some are
not, and worse, some are only a little bit magnetic :-)

Once you get past that there is no telling as Aluminum, for example,
is nonmagnetic, usually does not spark, and is available in an amazing
number of alloys and treatments. In the aircraft industry there was
even a copper-aluminum alloy that corroded rapidly in itself but was
coated with a very thin of aluminum on both sides which protected it.
See: https://en.wikipedia.org/wiki/Alclad

It is a complex subject.
--
cheers,

John B.

John B. writes:

... For normal environments, such as storage
in warehouses or non-temperature and humidity
controlled environments. Typically there
should not be more than 0.25 V difference in
the "Anodic Index"."

Aluminum - ~0.60, Aluminum - ~0.90

OK, should that be:

Chromium plated; tin plated; 12% chromium
type corrosion-resistant steels

for ~0.60 V?

--
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John B. writes:

Actually the only sure test is to have a lab
test the material

What about "if the brush leaves a mark, it is
too hard"?

If harder is more,

hair nylon brass steel

right?

Can you deduct or enclose the material from how
hard it is? Or can different materials be
virtually as hard, with two instances of the
same material differ substantially in
this respect?

The frame is often dull as is the crank and
nuts. The handle bar and saddle pole are often
shiny. The upper part of the fork is often not
shiny but still softer than the frame. The rims
sometimes shiny, sometimes soft-but-dull, quite
hard despite looking fragile. The fenders
almost always shiny and soft, and not just soft
because of their thinness, I think.
The handlebar and in particular the fenders
appear the most vulnerable to too hard
brushes...

--
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On Mon, 04 Jul 2016 05:27:02 +0200, Emanuel Berg
wrote:

John B. writes:

Actually the only sure test is to have a lab
test the material

What about "if the brush leaves a mark, it is
too hard"?

If harder is more,

hair nylon brass steel

right?

Yes, but at the same time the ability to remove material is the same.

Can you deduct or enclose the material from how
hard it is? Or can different materials be
virtually as hard, with two instances of the
same material differ substantially in
this respect?

The frame is often dull as is the crank and
nuts. The handle bar and saddle pole are often
shiny. The upper part of the fork is often not
shiny but still softer than the frame. The rims
sometimes shiny, sometimes soft-but-dull, quite
hard despite looking fragile. The fenders
almost always shiny and soft, and not just soft
because of their thinness, I think.
The handlebar and in particular the fenders
appear the most vulnerable to too hard
brushes...

Corrosion depends very much on the material and what is causing it.
"Normal" corrosion - rust, etc. varies, a ferrous material, iron,
steel, etc. form iron oxide (rust) and ultimately will rust completely
away. Pure aluminum, on the other hand, forms a thin layer of aluminum
oxide on the surface (looks dull) which protects it from further
corrosion. Aluminum alloys can vary considerably depending on what the
alloying elements are. Brass and bronze vary considerably, again,
depending on the alloying elements.

The first ships that were sheathed with metal used lead however and
the iron rudder pintles were eaten away.


--
cheers,

John B.

On Mon, 04 Jul 2016 05:10:44 +0200, Emanuel Berg
wrote:

John B. writes:

... For normal environments, such as storage
in warehouses or non-temperature and humidity
controlled environments. Typically there
should not be more than 0.25 V difference in
the "Anodic Index"."

Aluminum - ~0.60, Aluminum - ~0.90

OK, should that be:

Chromium plated; tin plated; 12% chromium
type corrosion-resistant steels

for ~0.60 V?

Are you going overboard here? My "second" Bangkok Bike was built in,
perhaps the mid 1900's and as far as I could tell probably had the
original aluminum wheels, with chrome or nickel plated nipples and
stainless spokes. The bike obviously came from Japan which does have a
lot of rain. No visible corrosion.
--
cheers,

John B.

John B. writes:

What about "if the brush leaves a mark, it is
too hard"?

If harder is more,
hair nylon brass steel

right?

Yes, but at the same time the ability to
remove material is the same.

In the open, yes, but what if the material you
wish to remove is somehow intermingled with
other material that protects it? Perhaps the
nylon brush wont get past it, but the steel
brush will, however question remains if there
is a downside to that...

Corrosion depends very much on the material
and what is causing it. "Normal" corrosion -
rust, etc. varies, a ferrous material, iron,
steel, etc. form iron oxide (rust) and
ultimately will rust completely away.
Pure aluminum, on the other hand, forms
a thin layer of aluminum oxide on the surface
(looks dull) which protects it from further
corrosion. Aluminum alloys can vary
considerably depending on what the alloying
elements are. Brass and bronze vary
considerably, again, depending on the
alloying elements.

The first ships that were sheathed with metal
used lead however and the iron rudder pintles
were eaten away.

OK, so aluminum is sheathed with an alloy which
isolates the aluminum from the potential
electrolyte, so there can't be the battery
effect and thus no corrosion?

So probably the alloy on my rim was worn out or
not in 100% effect?

Perhaps someone cleaned the rim in
a heavy-handed way (e.g., the steel brush)
which damaged the alloy?

--
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John B. writes:

... For normal environments, such as
storage in warehouses or non-temperature
and humidity controlled environments.
Typically there should not be more than
0.25 V difference in the "Anodic Index"."

Aluminum - ~0.60, Aluminum - ~0.90

OK, should that be:

Chromium plated; tin plated; 12% chromium
type corrosion-resistant steels

for ~0.60 V?

Are you going overboard here?

Ha, no, it is what I found on the page to which
you provided the URL when I searched for
"0.60"!

Because you wrote "Aluminum" twice:

Aluminum - ~0.60, Aluminum - ~0.90

Before that, you said IIUC that for corrosion
to happen, there should be a difference between
the metals of 0.25 V, and there is such
a difference between 0.60 V and 0.90 V, only
I think you meant to write something else and
not aluminum twice!

My "second" Bangkok Bike was built in,
perhaps the mid 1900's and as far as I could
tell probably had the original aluminum
wheels, with chrome or nickel plated nipples
and stainless spokes. The bike obviously came
from Japan which does have a lot of rain.
No visible corrosion.

OK, cool

--
underground experts united .... http://user.it.uu.se/~embe8573
Emacs Gnus Blogomatic ......... http://user.it.uu.se/~embe8573/blogomatic
- so far: 56 Blogomatic articles -

On Tue, 05 Jul 2016 21:48:23 +0200, Emanuel Berg
wrote:

John B. writes:

What about "if the brush leaves a mark, it is
too hard"?

If harder is more,
hair nylon brass steel

right?

Yes, but at the same time the ability to
remove material is the same.

In the open, yes, but what if the material you
wish to remove is somehow intermingled with
other material that protects it? Perhaps the
nylon brush wont get past it, but the steel
brush will, however question remains if there
is a downside to that...

Corrosion depends very much on the material
and what is causing it. "Normal" corrosion -
rust, etc. varies, a ferrous material, iron,
steel, etc. form iron oxide (rust) and
ultimately will rust completely away.
Pure aluminum, on the other hand, forms
a thin layer of aluminum oxide on the surface
(looks dull) which protects it from further
corrosion. Aluminum alloys can vary
considerably depending on what the alloying
elements are. Brass and bronze vary
considerably, again, depending on the
alloying elements.

The first ships that were sheathed with metal
used lead however and the iron rudder pintles
were eaten away.

OK, so aluminum is sheathed with an alloy which
isolates the aluminum from the potential
electrolyte, so there can't be the battery
effect and thus no corrosion?

No, I didn't say that all aluminum is sheathed, only certain alloys.
And all corrosion is not galvanic either. Many metals will corrode
(oxidize) with no dissimilar metals with in a hundred miles :-)

So probably the alloy on my rim was worn out or
not in 100% effect?

Perhaps someone cleaned the rim in
a heavy-handed way (e.g., the steel brush)
which damaged the alloy?

If it is an aluminum it is, or was, probably coated in some manner as
most aluminum bicycle stuff usually is. Part of you problem may be
that it was polished off or maybe just got old.

But I've never seen a problem with aluminum wheels. Not to say there
is none but I suspect it is probably fairly rare.
--
cheers,

John B.

On Tue, 05 Jul 2016 21:56:57 +0200, Emanuel Berg
wrote:

John B. writes:

... For normal environments, such as
storage in warehouses or non-temperature
and humidity controlled environments.
Typically there should not be more than
0.25 V difference in the "Anodic Index"."

Aluminum - ~0.60, Aluminum - ~0.90

OK, should that be:

Chromium plated; tin plated; 12% chromium
type corrosion-resistant steels

for ~0.60 V?

Are you going overboard here?

Ha, no, it is what I found on the page to which
you provided the URL when I searched for
"0.60"!

Because you wrote "Aluminum" twice:

Goodness! Do you want me to actually remember what I say (or post)?
:-)

Aluminum - ~0.60, Aluminum - ~0.90

Before that, you said IIUC that for corrosion
to happen, there should be a difference between
the metals of 0.25 V, and there is such
a difference between 0.60 V and 0.90 V, only
I think you meant to write something else and
not aluminum twice!

My "second" Bangkok Bike was built in,
perhaps the mid 1900's and as far as I could
tell probably had the original aluminum
wheels, with chrome or nickel plated nipples
and stainless spokes. The bike obviously came
from Japan which does have a lot of rain.
No visible corrosion.

OK, cool
--
cheers,

John B.

John B. writes:

No, I didn't say that all aluminum is
sheathed, only certain alloys. And all
corrosion is not galvanic either. Many metals
will corrode (oxidize) with no dissimilar
metals with in a hundred miles :-)

OK, so some alloys of aluminum are
sheathed/coated to protect them from rust and
oxidization (corrosion). This is common on
bikes. But sometimes there can still be
galvanic corrosion in the coating or normal
corrosion in the aluminum if the coating is
removed or gets old.

--
underground experts united .... http://user.it.uu.se/~embe8573
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