Don't know if I asked this question before, and it didn't get through, as I
have been having puter problems. How do I polish oxidized aluminum, as in a
boat hull? don't have to be mirror, just get it looking better.

Steve

"Steve B" fired this volley in news:jsqrpl$irm$1
@speranza.aioe.org:

How do I polish oxidized aluminum, as in a
boat hull? don't have to be mirror, just get it looking better.



The basic rule for polishing is: Use progressively finer abrasives, each
being selected to easily take out the scratches from the last. If you
don't have any serious "grinding" to do, a lamb's wool buffer starting out
with coarse rubbing compound, and working to ultra-fine, should do it.
(different pad for each compound).

LLoyd

Steve B wrote:
Don't know if I asked this question before, and it didn't get through, as I
have been having puter problems. How do I polish oxidized aluminum, as in a
boat hull? don't have to be mirror, just get it looking better.

Steve



Is it rough or just dull?

If rough you will need to start with actual abrasive and work back to
polish.

If it's just dull grab some Mothers mag/aluminum polish and go to work.
It will clean it up and make it shiny and wax it all at the same time.

--
Steve W.

Phosphoric acid diluted solution is the most practical method of removing
the dark oxide layer.. aluminum oxide is what many abrasive products are
made of, and not particularly easy or cost effective to attempt remval with
mechanical methods.

--
WB
..........



"Steve B" wrote in message
...
Don't know if I asked this question before, and it didn't get through, as
I have been having puter problems. How do I polish oxidized aluminum, as
in a boat hull? don't have to be mirror, just get it looking better.

Steve

"Wild_Bill" fired this volley in
news
aluminum oxide is what many abrasive products are
made of, and not particularly easy or cost effective to attempt remval
with mechanical methods.



Unless you "flux" the surface _while_ you are cleaning, the oxide layer
will re-form as rapidly as you clean. Aluminum is extraordinarily
reactive with water and oxygen, and reacts almost instantaneously when a
fresh layer is uncovered.

Bases are actually more effective at removing aluminum oxide than are
acids.

It's the base/Al2O3 reaction in aluminum-bearing pyrotechnic compositions
that can cause thermal run-away in the presence of moisture. The Al2O3
protects the surface from reacting with water, but basic solutions
quickly dissolve it (but not the base metal, as would an acid), exposing
the pure metal to water attack.

LLoyd

Lloyd E. Sponenburgh wrote:
"Wild_Bill" fired this volley in
news
aluminum oxide is what many abrasive products are
made of, and not particularly easy or cost effective to attempt remval
with mechanical methods.



Unless you "flux" the surface _while_ you are cleaning, the oxide layer
will re-form as rapidly as you clean. Aluminum is extraordinarily
reactive with water and oxygen, and reacts almost instantaneously when a
fresh layer is uncovered.

Bases are actually more effective at removing aluminum oxide than are
acids.

It's the base/Al2O3 reaction in aluminum-bearing pyrotechnic compositions
that can cause thermal run-away in the presence of moisture. The Al2O3
protects the surface from reacting with water, but basic solutions
quickly dissolve it (but not the base metal, as would an acid), exposing
the pure metal to water attack.

LLoyd

That is what Mothers does. It chemically and mechanically removes the
oxides and seals the aluminum at the same time. Tho only real problem is
that it can make some items far to bright. Something like a brushed
surface no longer looks brushed.

--
Steve W.

"Steve W." wrote

That is what Mothers does. It chemically and mechanically removes the
oxides and seals the aluminum at the same time. Tho only real problem is
that it can make some items far to bright. Something like a brushed
surface no longer looks brushed.

--
Steve W.

I just bought a polishing wheel at the ridiculous price of $9. I think I
will go with the Mother's and call it good. I could be spending the money
on fishing supplies.

Sheesh, a good LED for crappie fishing is $52.

Goddam liberal capitalists.

Steve

Steve B wrote:
"Steve W." wrote

That is what Mothers does. It chemically and mechanically removes the
oxides and seals the aluminum at the same time. Tho only real problem is
that it can make some items far to bright. Something like a brushed
surface no longer looks brushed.

--
Steve W.

I just bought a polishing wheel at the ridiculous price of $9. I think I
will go with the Mother's and call it good. I could be spending the money
on fishing supplies.

Sheesh, a good LED for crappie fishing is $52.

Goddam liberal capitalists.

Steve



If you're looking at submersible LED lights you can DIY one cheaper.
Grab a chunk of clear plastic tube. A couple of the stick on light
strips sold for ricer dressing in the auto parts store (green seems to
work well). Stick the lights to a strip of tin, connect up some power
line and install a cap on that end and make sure it's sealed. Cut the
tube so it is short enough to cover the lights but leave some room on
the open end.

Now to add some weight. Install a temporary cap on the open end and toss
the light into the water in a tub/drum. Chances are it will lay over and
float. Pull it out and add some lead shot to the bottom and try again.
this will take a few tries depending on the exact lights and tube
buoyancy. You want it to be just a bit heavy, that way you can add a
float to set the depth it sets at.

The power cord also serves as a tether and allows a larger power supply
than many of the store built types.

I've also used those strips in red and blue up under the gunwales for
interior lighting.

--
Steve W.

In my experience with diluted phosphoric acid solutions used to etch metals,
the metals are not susceptible to immediate, or quick, oxidization after
treatment.

I dunno what the composition is, but truck owners use a chemical solution to
remove oxidation from those pretty uncoated aluminum dump beds and trailers.

I don't see how running a polisher and slinging paste is going to be more
effective than completely stripping away all of the oxidation chemically.
Some baking soda can be used to neutralize the wash-off.

Of course a bare aluminum boat hull isn't going to remain pristine for long
in use, but it will be clean if other preventative measures are taken.

--
WB
..........



"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
. 3.70...
"Wild_Bill" fired this volley in
news
aluminum oxide is what many abrasive products are
made of, and not particularly easy or cost effective to attempt remval
with mechanical methods.



Unless you "flux" the surface _while_ you are cleaning, the oxide layer
will re-form as rapidly as you clean. Aluminum is extraordinarily
reactive with water and oxygen, and reacts almost instantaneously when a
fresh layer is uncovered.

Bases are actually more effective at removing aluminum oxide than are
acids.

It's the base/Al2O3 reaction in aluminum-bearing pyrotechnic compositions
that can cause thermal run-away in the presence of moisture. The Al2O3
protects the surface from reacting with water, but basic solutions
quickly dissolve it (but not the base metal, as would an acid), exposing
the pure metal to water attack.

LLoyd

"Wild_Bill" fired this volley in
:



I dunno what the composition is, but truck owners use a chemical
solution to remove oxidation from those pretty uncoated aluminum dump
beds and trailers.

Phosphoric acid is best used on ferrous metals. Any kind of acid is the
wrong choice for aluminum.

Bases are most effectively used to clean aluminum. Truck wheel cleaner,
AC evaporator cleaner, and sink drain un-plugger are all the same stuff;
potassium hydroxide or sodium hydroxide in solution with water and some
detergent.

Acids preferentially attack the metal while leaving the oxide intact
until the metal undercuts the oxide, and it just falls off the surface in
pieces.

Bases preferentially attack the oxide very rapidly, actually dissolving
the Al2O3 while slowly attacking the metal.

AND, I think you have not a clue what aluminum oxide looks like, or you'd
not have made this statement --

In my experience with diluted phosphoric acid solutions used to etch
metals, the metals are not susceptible to immediate, or quick,
oxidization after treatment.

Bill, aluminum oxide, when it forms on _clean_ aluminum, forms in mere
seconds (just two or three, really), and is perfectly transparent and
clear ("water white" is the term that combines both).

Although impurities make them colored red or blue, you do know, don't
you, that rubies and sapphires are aluminum oxide -- right?

The "nasty-looking stuff" you see on corroded aluminum is NOT aluminum
oxide, but salts of aluminum remaining from other attacks on the metal
besides from oxygen -- like chlorides or phosphides.

LLoyd

On Thu, 05 Jul 2012 05:52:37 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

"Wild_Bill" fired this volley in
:



I dunno what the composition is, but truck owners use a chemical
solution to remove oxidation from those pretty uncoated aluminum dump
beds and trailers.

Phosphoric acid is best used on ferrous metals. Any kind of acid is the
wrong choice for aluminum.

Bases are most effectively used to clean aluminum. Truck wheel cleaner,
AC evaporator cleaner, and sink drain un-plugger are all the same stuff;
potassium hydroxide or sodium hydroxide in solution with water and some
detergent.


The caustic concentration must be very low in those products. I
worked on caustic soda production in R&D decades ago. In 10% NaOH
solution, aluminum very actively reacts, releasing hydrogen gas.

Don't use lye on your aluminum.

Pete Keillor

Acids preferentially attack the metal while leaving the oxide intact
until the metal undercuts the oxide, and it just falls off the surface in
pieces.

Bases preferentially attack the oxide very rapidly, actually dissolving
the Al2O3 while slowly attacking the metal.

AND, I think you have not a clue what aluminum oxide looks like, or you'd
not have made this statement --

In my experience with diluted phosphoric acid solutions used to etch
metals, the metals are not susceptible to immediate, or quick,
oxidization after treatment.

Bill, aluminum oxide, when it forms on _clean_ aluminum, forms in mere
seconds (just two or three, really), and is perfectly transparent and
clear ("water white" is the term that combines both).

Although impurities make them colored red or blue, you do know, don't
you, that rubies and sapphires are aluminum oxide -- right?

The "nasty-looking stuff" you see on corroded aluminum is NOT aluminum
oxide, but salts of aluminum remaining from other attacks on the metal
besides from oxygen -- like chlorides or phosphides.

LLoyd

Pete Keillor fired this volley in
:

The caustic concentration must be very low in those products.

They are, indeed, Pete. But "lye" is what it is. It's usually potash
lye, not soda lye, but either will work. The reason is the resultant
sodium salts are hygroscopic and can cause corrosion after the cleaning.
Proper rinsing can prevent that, but it has to be thorough. Thus, in
industrial settings, the sodium version is less expensive, and
satisfactory. For "field work", the potassium version is preferrable.


Lloyd