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  #81   Report Post  
Old May 19th 04, 11:36 PM
George
 
Posts: n/a
Default Test Results was Salt and vinegar for rust removal

Check your inorganic chemistry books under electronegativity. Sodium's
about as good as it gets, iron and copper not in the same league. Of
course it helps to have a good acid electrolyte in your cell.

Now try cleaning your silver with baking soda in an aluminum pan....

"Dan White" wrote in message
et...
First of all let me say that my interest in this thread, started by Sandy,
was caused by my own questioning of why salt helped clean copper pots with
vinegar.




  #82   Report Post  
Old May 20th 04, 03:51 AM
Sandy
 
Posts: n/a
Default Test Results was Salt and vinegar for rust removal

On Wed, 19 May 2004 20:27:09 GMT, "Dan White"
posted:

First of all let me say that my interest in this thread, started by Sandy,


Nope, I merely interjected my question about the need for salt into an
already existing thread. But I see what you mean.

was caused by my own questioning of why salt helped clean copper pots with
vinegar. Months ago I poured vinegar on a copper pot and it did nothing.
Then I sprinkled salt on, and the oxides just wiped away.


Wiped away with a cloth? The salt may have been acting as a scourer?
Copper is the other side of hydrogen in the electrochemical reactivity
table, so perhaps there is some difference here with iron?

I figure whatever
mechanism was working there is probably not that different from what happens
with iron.


Except for what I said above.

So on with my not-so-scientifically-controlled test:

I didn't have any rusted nails, but I did find two old 1.25 lb free weights.
These are 4" in diameter with a 1" hole for the barbell to go through. The
annular region between this hole and the outer edge of the weight was
recessed and could hold maybe a tablespoon worth of liquid, possibly more.
The annular region was embossed with the manufacturer's name and the weight.
Each weight was rusted moderately and had about the same amount of rust.
This means that there is more rust than you could casually remove, but not
so much that the weight had deep pits.

I poured vinegar into both, and then added an excess of salt to one of them.
Within hours, both were effervescing slightly. (They had bubbles collecting
on the surface). Note that this was done in contact with air, and with
plenty of surface area. After 48 hours I poured the liquid out of each into
test tube like containers. What I observe is that the vinegar/salt sample
was a light yellowish/orange color, and contained a fair amount of black
flecks and little chunks, in addition to some very small black particles.
On the other hand, the vinegar/no salt solution was a deep red color, very
different from the vinegar/salt sample. It had no flecks or chunks of black
material, but did have a fair amount of very fine, small black particles.
In both cases, black material built up on the edges of the liquid, and also
on some of the submerged surfaces.

I cleaned the weights by hand


Now this is perhaps the most important step and you have not
elaborated. How did you clean these things? The salt crystals can act
as a scourer, so if you wiped them with a rag....

and observed that the rust was gone from both,
but the vinegar/salt weight looked SLIGHTLY cleaner. I then used a brass
brush to clean them up further. After drying them out, it appears that the
vinegar/salt weight is a little brighter looking. The vinegar only weight
looks darker, as if there is dark material caught up in the fine pits and
crevices of the weight.


Could be that more of the orange rust had dissolved leaving the black
magnetite (Fe3O4), and the salt and vinegar dissolved less of this
orange rust leaving it appearing lighter. Both my examples seem
minutely more orange (lighter colour) than the non treated parts of
the nails.

Overall I'd say that there is a definite difference between the two as one
liquid was light yellow or orange, and the other was deep red. The
vinegar/salt weight also looked a little cleaner, but it is a very slight
difference. It could be that these old weights just looked a little
different from the start.

What caused the red color in one and not the other? Is the iron chloride
complex colorless, while FeCl3 is red?


I would guess that they are the same colour, containing the same
coloured ion Fe+++, but I'm not sure. I'm not even sure that this iron
chloride complex exists, as my question as to what happens to all that
excess Na+ was never answered.

My vinegar-only is definitely effervescing slightly more than the salt
and vinegar as seen this morning by swirling the bubbles away and
looking again in ten minutes for new bubbles to form.
Previously, effervescence appeared roughly similar and quite slight.

Sorry for being long-winded. Hope this spurs some ideas.

dwhite
PS. I might add clean water to each next to see if there is any difference
in corrosion rate as postulated by Sandy.


My reading suggests that the salt-treated article will rust more, even
if left dry. This is the problem, as the salt in the minute pits will
attract atmospheric moisture and act as electrolyte in minute
electrochemical cells. This will happen more in some alloys than
others.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

My experiment was with very rusted nails.

The vinegar only solution is brown(orange) and the salt and vinegar is
pale yellow. Effervescence is still going ever more strongly (though
still quite weak) at 46 hours. There seems to be more black specks
floating in the salted version. This may have been due to an original
difference in the nails. Both have a few rust particles on the bottom
of the tumblers.
The nails are imperceptibly different from when I put them in the
solutions -- slightly more yellow where the solutions have acted, but
still very heavily rusted.

I found that salt perhaps inhibits the process slightly, (except,
perhaps, as a scourer when the article is wiped with a rag?)
I worry about that salt in the rust pits, and so personally would
bever use salt on anything of mine that I valued.

My conclusion is that this procedure is useless for heavily rusted
articles. And salt makes an insignificant difference.

A wire brush and/or electrolysis might be a better way to go.

Thanks for an interesting exchange, Dan.


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Dan:
I have
some rusted metal soaking for about 36 hours now. I'll stop it Wed
afternoon and see what I get. I'll let you know, fwiw.


Sandy:
I'm now getting a bit of effervescence in mine. Carbonates dissolving,
I guess. That's a more promising sign, but 28 hours shows very little
cleaning. Not long ago, I stuck a very rusted hose clamp
(hydraulically applied) in vinegar in the hope that it would fall
apart. What it did do was to make the non-rusted chromed areas nice
and shiny. As there was still a lot of metal left, and not all rust as
it originally seemed, it required 3000 rpm of an 8" alumina wheel

My impression so far is that the salt impedes the derusting process.
I have read in places that salt is added to vinegar as a mild abrasive
when rubbing a rusted item clean. This is a very different process
than the one claimed in this thread.


Sandy:
That salt and vinegar are useless for derusting rusty tools?
Pretty much, I would contend, so far.

That Charlie was being a whinging busybody by complaining about our
discussion?
Yep, see my reponse to Jim.



"Jim Wilson" wrote in message
k.net...
Sandy wrote...
Jim Wilson posted:

Hyperbole, perhaps?

Nope, comparative. Cf dropping a rock on your foot

Ok, perhaps more complex than dropping a rock on your foot, but that
doesn't say a whole lot, does it? (G)

My conclusion so far is that using vinegar to clean off rust is a
waste of bloody time

It certainly is if you watch it. (G)

In the context of whining that our discussion was OT for this

forum.
Otherwise, what was the aim of his message?

That wasn't the context. He started by disagreeing with your

assertion
that "What we need explaining is why the presence of sodium chloride

in
the vinegar is advantageous." He noted that "we" non-chemist
woodworkers
do not need that explained at all. We need only know whether it

works,
not why.

Indeed, even a correct, lucid, and perfectly presented explanation
would
be of limited utility to the majority, although it might well be
interesting to many of us. An inconclusive, jargon-filled technical
debate would have to have considerably less utility, wouldn't you
agree?

Only afterward did he observe that the thread had wandered into OT
territory, and even then he did not suggest aborting the thread, but
rather that the subject line should have been altered.

Don't get me wrong -- personally, I am quite interested in the
discussion, and have been following the thread closely, but

obviously I
do have a penchant for useless academic debate :-). I interjected
because
I felt your take on Charlie's post was wrong, and that the points he
was
really trying to make were valid, to wit: 1) most readers of this NG
neither need nor want to understand this stuff, and 2) the thread

has
drifted off topic for this NG. I still want to hear it.

Jim






  #83   Report Post  
Old May 20th 04, 04:11 AM
Sandy
 
Posts: n/a
Default Test Results was Salt and vinegar for rust removal

On Wed, 19 May 2004 17:36:16 -0400, "George" [email protected] posted:

Check your inorganic chemistry books under electronegativity. Sodium's
about as good as it gets, iron and copper not in the same league.


Although iron and copper straddle hydrogen, which is an important
watershed.
Very few sodium tools available

Of
course it helps to have a good acid electrolyte in your cell.


That would be acetic acid?
H+ is surely what you need to dissolve insoluble
carbonates/hydroxides/oxides?
(Along with an anion that does not have insoluble salts with the iron)

Now try cleaning your silver with baking soda in an aluminum pan....


BBbbbbut the topic was rust

"Dan White" wrote in message
. net...
First of all let me say that my interest in this thread, started by Sandy,
was caused by my own questioning of why salt helped clean copper pots with
vinegar.



  #84   Report Post  
Old May 20th 04, 05:05 AM
Dan White
 
Posts: n/a
Default Test Results was Salt and vinegar for rust removal

"Sandy" wrote in message
...

was caused by my own questioning of why salt helped clean copper pots

with
vinegar. Months ago I poured vinegar on a copper pot and it did nothing.
Then I sprinkled salt on, and the oxides just wiped away.


Wiped away with a cloth? The salt may have been acting as a scourer?


The salt could be a scouring agent, but I don't think this is the main
benefit of salt. If you pour the salt on, you see small regions around each
grain where the rust is dissolving, even before you touch the pot with a
sponge.

Copper is the other side of hydrogen in the electrochemical reactivity
table, so perhaps there is some difference here with iron?

I figure whatever
mechanism was working there is probably not that different from what

happens
with iron.


Except for what I said above.


Yes, for sure that could be it. I was hoping not to relearn every
electronegativity etc etc.


So on with my not-so-scientifically-controlled test:

I didn't have any rusted nails, but I did find two old 1.25 lb free

weights.
These are 4" in diameter with a 1" hole for the barbell to go through.

The
annular region between this hole and the outer edge of the weight was
recessed and could hold maybe a tablespoon worth of liquid, possibly

more.
The annular region was embossed with the manufacturer's name and the

weight.
Each weight was rusted moderately and had about the same amount of rust.
This means that there is more rust than you could casually remove, but

not
so much that the weight had deep pits.

I poured vinegar into both, and then added an excess of salt to one of

them.
Within hours, both were effervescing slightly. (They had bubbles

collecting
on the surface). Note that this was done in contact with air, and with
plenty of surface area. After 48 hours I poured the liquid out of each

into
test tube like containers. What I observe is that the vinegar/salt

sample
was a light yellowish/orange color, and contained a fair amount of black
flecks and little chunks, in addition to some very small black particles.
On the other hand, the vinegar/no salt solution was a deep red color,

very
different from the vinegar/salt sample. It had no flecks or chunks of

black
material, but did have a fair amount of very fine, small black particles.
In both cases, black material built up on the edges of the liquid, and

also
on some of the submerged surfaces.

I cleaned the weights by hand


Now this is perhaps the most important step and you have not
elaborated. How did you clean these things? The salt crystals can act
as a scourer, so if you wiped them with a rag....


I honestly don't think salt scouring had much to do with it. After I dumped
out the acid I ran them under water and literally rubbed them with my
fingers. It was really more of just brushing the black bits off the metal.
I think all the salt had dissolved in the acid after 48 hours, anyway. Now,
I next cleaned the weights with a brass brush, so that's where some scouring
comes in. Even so, the vinegar/salt weight was cleaner, but I wouldn't say
so conclusively. It really could just have been a difference in the two
weights from the start. If there were any scouring other than the brass
brush, it would probably be more from the bits of Fe2O3 or whatever it is
that turns black.


and observed that the rust was gone from both,
but the vinegar/salt weight looked SLIGHTLY cleaner. I then used a brass
brush to clean them up further. After drying them out, it appears that

the
vinegar/salt weight is a little brighter looking. The vinegar only

weight
looks darker, as if there is dark material caught up in the fine pits and
crevices of the weight.


snip

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

My experiment was with very rusted nails.

The vinegar only solution is brown(orange) and the salt and vinegar is
pale yellow. Effervescence is still going ever more strongly (though
still quite weak) at 46 hours. There seems to be more black specks
floating in the salted version. This may have been due to an original
difference in the nails. Both have a few rust particles on the bottom
of the tumblers.
The nails are imperceptibly different from when I put them in the
solutions -- slightly more yellow where the solutions have acted, but
still very heavily rusted.

I found that salt perhaps inhibits the process slightly, (except,
perhaps, as a scourer when the article is wiped with a rag?)
I worry about that salt in the rust pits, and so personally would
bever use salt on anything of mine that I valued.

My conclusion is that this procedure is useless for heavily rusted
articles. And salt makes an insignificant difference.

A wire brush and/or electrolysis might be a better way to go.


It is interesting, though, to note that in my experiment the vinegar/salt
solution was pale orange, while the vinegar only was deep red. I'm
interested to see how it ends up in your test. There is *definitely*
something different going on in each case, and it would be interesting to
know what that is. I wonder if the vinegar only is dissolving more Fe
metal, and is somehow inhibited by the salt. Maybe this needs to be done in
the absence of air, as the other poster suggested. Maybe the results would
be different.

Thanks for an interesting exchange, Dan.

Ditto. You make a good point about salt corrosion. Good to know.

dwhite


  #85   Report Post  
Old May 20th 04, 12:56 PM
George
 
Posts: n/a
Default Test Results was Salt and vinegar for rust removal

Sodium salts are quite soluble versus iron, you know. You've had ion
replacement going on as well as reduction.

"Dan White" wrote in message
et...

Yes, for sure that could be it. I was hoping not to relearn every
electronegativity etc etc.

It is interesting, though, to note that in my experiment the vinegar/salt
solution was pale orange, while the vinegar only was deep red. I'm
interested to see how it ends up in your test. There is *definitely*
something different going on in each case, and it would be interesting to
know what that is. I wonder if the vinegar only is dissolving more Fe
metal, and is somehow inhibited by the salt. Maybe this needs to be done

in
the absence of air, as the other poster suggested. Maybe the results

would
be different.





  #86   Report Post  
Old May 20th 04, 04:00 PM
WillaimC
 
Posts: n/a
Default Test Results was Salt and vinegar for rust removal

Muriatic acid of the sort used for concrete work removes rust
completely and in a fairly short order. I dropped some fine thread
rusty bolts in this acid and left it overnight and the threads screwed
into the correct size nut with no problem so the metal was not eaten
away. The only posssible downside is that the metal is turned to an
even light grey, possibly from very light etching
  #87   Report Post  
Old May 21st 04, 09:08 AM
Sandy
 
Posts: n/a
Default Test Results was Salt and vinegar for rust removal

On Thu, 20 May 2004 09:51:42 +0800, Sandy posted:

Final report on the great Salt and Vinegar test

Before I hoik it all out and consign the tumblers to the dishwasher, I
thought I would describe conditions (About 75 hours, I think)

The salt-and-vinegar solution has just about NO colour to it; it has
NO effervescence; and a black scum on the surface. The nails are no
different from before treatment except that they have gone blacker.
There is a an amount of rust flakes on the bottom.

The "vinegar-only" still has slight effervescence occurring, and is a
strong orange/red colour. The nails are no different except a little
more rusty coloured. There is a similar amount of rust flakes on the
bottom.

As a final twist, I decanted some of the clear orange liquid from the
vinegar-only solution and added excess salt. Lo and behold, a black
precipitate occurred turning the solution almost chocolate brown and
opaque. I will leave this to settle, coz what I'm trying to see is if
this purported ferric chloride complex is less orange than the
straight ferric ion. So far, half an hour, the red colour seems to be
persisting, so unless there is a marked loss of colour, that ferric
chloride complex has not been demonstrated. Although the lack of
colour in the vinegar-salt test could be because no ferric ions have
been formed at all, just black ?magnetite?

My conclusion is that although the vinegar and the salt-and-vinegar
cause some of the loose rust to fall off the very rusty iron, the
treated surface is by no means cleaned. The appearance is not even
perceptibly changed. I can't determine if one works better than the
other, but from the colours of the solution and the rust and the
lesser effervescence, I would conclude the the salt impedes the
dissolution process.

I will rinse these nails and stick them back out in the rain and see
which ones fall apart quicker.








and observed that the rust was gone from both,
but the vinegar/salt weight looked SLIGHTLY cleaner. I then used a brass
brush to clean them up further. After drying them out, it appears that the
vinegar/salt weight is a little brighter looking. The vinegar only weight
looks darker, as if there is dark material caught up in the fine pits and
crevices of the weight.


Could be that more of the orange rust had dissolved leaving the black
magnetite (Fe3O4), and the salt and vinegar dissolved less of this
orange rust leaving it appearing lighter. Both my examples seem
minutely more orange (lighter colour) than the non treated parts of
the nails.

Overall I'd say that there is a definite difference between the two as one
liquid was light yellow or orange, and the other was deep red. The
vinegar/salt weight also looked a little cleaner, but it is a very slight
difference. It could be that these old weights just looked a little
different from the start.

What caused the red color in one and not the other? Is the iron chloride
complex colorless, while FeCl3 is red?


I would guess that they are the same colour, containing the same
coloured ion Fe+++, but I'm not sure. I'm not even sure that this iron
chloride complex exists, as my question as to what happens to all that
excess Na+ was never answered.

My vinegar-only is definitely effervescing slightly more than the salt
and vinegar as seen this morning by swirling the bubbles away and
looking again in ten minutes for new bubbles to form.
Previously, effervescence appeared roughly similar and quite slight.

Sorry for being long-winded. Hope this spurs some ideas.

dwhite
PS. I might add clean water to each next to see if there is any difference
in corrosion rate as postulated by Sandy.


My reading suggests that the salt-treated article will rust more, even
if left dry. This is the problem, as the salt in the minute pits will
attract atmospheric moisture and act as electrolyte in minute
electrochemical cells. This will happen more in some alloys than
others.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

My experiment was with very rusted nails.

The vinegar only solution is brown(orange) and the salt and vinegar is
pale yellow. Effervescence is still going ever more strongly (though
still quite weak) at 46 hours. There seems to be more black specks
floating in the salted version. This may have been due to an original
difference in the nails. Both have a few rust particles on the bottom
of the tumblers.
The nails are imperceptibly different from when I put them in the
solutions -- slightly more yellow where the solutions have acted, but
still very heavily rusted.

I found that salt perhaps inhibits the process slightly, (except,
perhaps, as a scourer when the article is wiped with a rag?)
I worry about that salt in the rust pits, and so personally would
bever use salt on anything of mine that I valued.

My conclusion is that this procedure is useless for heavily rusted
articles. And salt makes an insignificant difference.

A wire brush and/or electrolysis might be a better way to go.

Thanks for an interesting exchange, Dan.


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Dan:
I have
some rusted metal soaking for about 36 hours now. I'll stop it Wed
afternoon and see what I get. I'll let you know, fwiw.


Sandy:
I'm now getting a bit of effervescence in mine. Carbonates dissolving,
I guess. That's a more promising sign, but 28 hours shows very little
cleaning. Not long ago, I stuck a very rusted hose clamp
(hydraulically applied) in vinegar in the hope that it would fall
apart. What it did do was to make the non-rusted chromed areas nice
and shiny. As there was still a lot of metal left, and not all rust as
it originally seemed, it required 3000 rpm of an 8" alumina wheel

My impression so far is that the salt impedes the derusting process.
I have read in places that salt is added to vinegar as a mild abrasive
when rubbing a rusted item clean. This is a very different process
than the one claimed in this thread.


Sandy:
That salt and vinegar are useless for derusting rusty tools?
Pretty much, I would contend, so far.

That Charlie was being a whinging busybody by complaining about our
discussion?
Yep, see my reponse to Jim.



"Jim Wilson" wrote in message
k.net...
Sandy wrote...
Jim Wilson posted:

Hyperbole, perhaps?

Nope, comparative. Cf dropping a rock on your foot

Ok, perhaps more complex than dropping a rock on your foot, but that
doesn't say a whole lot, does it? (G)

My conclusion so far is that using vinegar to clean off rust is a
waste of bloody time

It certainly is if you watch it. (G)

In the context of whining that our discussion was OT for this

forum.
Otherwise, what was the aim of his message?

That wasn't the context. He started by disagreeing with your

assertion
that "What we need explaining is why the presence of sodium chloride

in
the vinegar is advantageous." He noted that "we" non-chemist
woodworkers
do not need that explained at all. We need only know whether it

works,
not why.

Indeed, even a correct, lucid, and perfectly presented explanation
would
be of limited utility to the majority, although it might well be
interesting to many of us. An inconclusive, jargon-filled technical
debate would have to have considerably less utility, wouldn't you
agree?

Only afterward did he observe that the thread had wandered into OT
territory, and even then he did not suggest aborting the thread, but
rather that the subject line should have been altered.

Don't get me wrong -- personally, I am quite interested in the
discussion, and have been following the thread closely, but

obviously I
do have a penchant for useless academic debate :-). I interjected
because
I felt your take on Charlie's post was wrong, and that the points he
was
really trying to make were valid, to wit: 1) most readers of this NG
neither need nor want to understand this stuff, and 2) the thread

has
drifted off topic for this NG. I still want to hear it.

Jim






  #88   Report Post  
Old May 21st 04, 06:32 PM
charlie b
 
Posts: n/a
Default Test Results was Salt and vinegar for rust removal

Sandy wrote:

On Thu, 20 May 2004 09:51:42 +0800, Sandy posted:

Final report on the great Salt and Vinegar test

Before I hoik it all out and consign the tumblers to the dishwasher, I
thought I would describe conditions (About 75 hours, I think)


(major snippage)

Sir:

You have WAY too much spare time on your hands.

Having said that
The effervesence (sp?) may play an important role
in rust removal , small bubbles forming in fine nooks
and crannies of rust on the piece. As they get bigger
they can mechanically, rather than chemically, loosen
rust particles - similar to cavitation.

However you get the rust off with an aqueous (sp?)
solution, after rinsing and hand drying, wipe things
down with a paper towel soaked with alcohol. Wipe
things down again with a dry towel. The alcohol will
grab any water left after the first "wiped dry".

charlie b
  #89   Report Post  
Old May 21st 04, 08:38 PM
Ken Muldrew
 
Posts: n/a
Default Test Results was Salt and vinegar for rust removal

Sandy wrote:

My conclusion is that although the vinegar and the salt-and-vinegar
cause some of the loose rust to fall off the very rusty iron, the
treated surface is by no means cleaned.


That's a shame, but salt and vinegar is delicious on chips!

Ken Muldrew

(remove all letters after y in the alphabet)
  #90   Report Post  
Old May 21st 04, 10:20 PM
Dan White
 
Posts: n/a
Default Test Results was Salt and vinegar for rust removal

"Sandy" wrote in message
...

My conclusion is that although the vinegar and the salt-and-vinegar
cause some of the loose rust to fall off the very rusty iron, the
treated surface is by no means cleaned. The appearance is not even
perceptibly changed. I can't determine if one works better than the
other, but from the colours of the solution and the rust and the
lesser effervescence, I would conclude the the salt impedes the
dissolution process.


Interesting, despite what the others say! Your test about jives with my
results, the most notable difference being the nearly clear vinegar/salt
solution and the dark red (in my case) vinegar only solution. I would say
that the iron did come clean by using the vinegar solutions, but required
some brushing to really get all the rust off. I think it came cleaner than
it would have had I not used the vinegar, but maybe there are better
mechanical ways of doing that, or using a little muriatic acid and being
very quick to rinse it off.

dwhite




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