lagagnon wrote:
I am about to refurbish an old Hy-Gain TH3-Mk3 Thunderbird tri-band
yagi. This yagi has been used in a coastal environment and thus the
aluminum is slightly pitted and most of the connecting hardware needs
replacing.

I figure steel wool would work fine for the aluminum tubing,

Avoid steel wool. Inevitably, it will leave little iron/steel fibers
behind, which will rust/corrode/react with the aluminum.

Use synthetic scrubbies (3M ScotchBrite) instead.


I know
how to test the traps, but I am wondering whether to use stainless
steel or galvanized hardware? Which would react least over time with
the aluminum? Also, I remember many years ago there is an electrical
joint compound stuff for using between the tubing sleeves - can anyone
please give me some brand names of this stuff?

Any other ideas appreciated....

Larry VE7EA

Jim Lux wrote:
lagagnon wrote:
I am about to refurbish an old Hy-Gain TH3-Mk3 Thunderbird tri-band
yagi. This yagi has been used in a coastal environment and thus the
aluminum is slightly pitted and most of the connecting hardware needs
replacing.

I figure steel wool would work fine for the aluminum tubing,

Avoid steel wool. Inevitably, it will leave little iron/steel fibers
behind, which will rust/corrode/react with the aluminum.

Hi Jim,

I keep hearing about steel wool rusting in/corroding Aluminum, but does
anyone have actual evidence? I've been looking on the web, and although
apparently using steel wool on AL will cause warts, bad breath, and the
downfall of the free world, all I've found is admonitions not to use it.
Maybe I'll try an experiment - I have some old antenna tubing.

There's just something a little strange about this. For the steel
particles to corrode the AL, they would have to detach, (easy enough)
settle into pores in the Aluminum at sizes small enough to do that,
(hmmm, those are pretty tiny steel particles) or have some odd property
of sticking to the AL despite cleaning. Then I guess it's a race between
rust and galvanic corrosion?


Use synthetic scrubbies (3M ScotchBrite) instead.

Bronze or stainless steel wool might be a good material to use. Boaters
use it on aluminum.

- 73 de Mike N3LI -

Michael Coslo wrote:
Jim Lux wrote:
lagagnon wrote:
I am about to refurbish an old Hy-Gain TH3-Mk3 Thunderbird tri-band
yagi. This yagi has been used in a coastal environment and thus the
aluminum is slightly pitted and most of the connecting hardware needs
replacing.

I figure steel wool would work fine for the aluminum tubing,

Avoid steel wool. Inevitably, it will leave little iron/steel fibers
behind, which will rust/corrode/react with the aluminum.

Hi Jim,

I keep hearing about steel wool rusting in/corroding Aluminum, but does
anyone have actual evidence? I've been looking on the web, and although
apparently using steel wool on AL will cause warts, bad breath, and the
downfall of the free world, all I've found is admonitions not to use it.
Maybe I'll try an experiment - I have some old antenna tubing.

Go for it.

There's just something a little strange about this. For the steel
particles to corrode the AL, they would have to detach, (easy enough)
settle into pores in the Aluminum at sizes small enough to do that,
(hmmm, those are pretty tiny steel particles) or have some odd property
of sticking to the AL despite cleaning.

steel is much harder than aluminum, so the little fibers jam into the
relatively soft aluminum and make their own holes.


Then I guess it's a race between
rust and galvanic corrosion?

Yep..



Use synthetic scrubbies (3M ScotchBrite) instead.

Bronze or stainless steel wool might be a good material to use. Boaters
use it on aluminum.

- 73 de Mike N3LI -



The other thing to keep in mind with this sort of thing is the expected
life. Hey, if it's only going to be up for a year or two or three, it
probably doesn't matter. If you're going to expect your grandchildren's
children to use it unchanged, a bit more care might be required.

On Apr 29, 10:37*am, Michael Coslo wrote:
Jim Lux wrote:
lagagnon wrote:
I am about to refurbish an old Hy-Gain TH3-Mk3 Thunderbird tri-band
yagi. This yagi has been used in a coastal environment and thus the
aluminum is slightly pitted and most of the connecting hardware needs
replacing.

I figure steel wool would work fine for the aluminum tubing,

Avoid steel wool. Inevitably, it will leave little iron/steel fibers
behind, which will rust/corrode/react with the aluminum.

* * * * Hi Jim,

I keep hearing about steel wool rusting in/corroding Aluminum, but does
anyone have actual evidence? I've been looking on the web, and although
apparently using steel wool on AL will cause warts, bad breath, and the
downfall of the free world, all I've found is admonitions not to use it.
Maybe I'll try an experiment - I have some old antenna tubing.

There's just something a little strange about this. For the steel
particles to corrode the AL, they would have to detach, (easy enough)
settle into pores in the Aluminum at sizes small enough to do that,
(hmmm, those are pretty tiny steel particles) or have some odd property
of sticking to the AL despite cleaning. Then I guess it's a race between
rust and galvanic corrosion?

Use synthetic scrubbies (3M ScotchBrite) instead.

Bronze or stainless steel wool might be a good material to use. Boaters
use it on aluminum.

* * * * - 73 de Mike N3LI -

When you scour with the steel wool it will cut into the soft Al and
break off. You wont know about it until it starts to rust. Some
aluminum alloys dont seem to have as much of a problem with this but
others do. Ive had it happen to me, warned someone who still tried it
and had no problem.

Jimmie

I keep hearing about steel wool rusting in/corroding Aluminum, but does
anyone have actual evidence?


Yeah, the mast on my sailboat as done by a previous owner of the boat.
It has some serious cosmetic corrosion and small pitting (but didn't
effect the mast's functionality) where the PO used steel wool to
remove some boat adhesive he accidently got on the mast. There were
small pits in that area. This is not as serious as aluminun to
stainless steel hardware bimetalic corrosion. SOP for a boat mast is
to used threaded bolts, not self tapping screws and to tap the hole.
Then we put in some version of Loctite (don't remember which one there
are many varieties of Loctite) designed for the purpose and sold at
boating stores among many other places. That minimized the bimetalic
corrosion effect. I never had any problems with the masts on my
sailboat after I enlarged the corroded holes a size larger and then
tapped them and put the SS machine screws in. Using anything other
than 316 SS screws is inviting disaster on a boat. Hardware starts to
fall off boats.

BTW my small sailboat sank last year, but that had nothing to do with
corrosion. My larger boat was donated to the Sea Scouts and I'm out
of sailing now. Wife (and crew) has had arthritis and had a triple
bypass a years ago. I just can't send her up the mast anymore :-).

Jon W3JT

The problem with stainless steel wool is that the consumer has little
control over what it actually is. There are many grades of stainless
and some grades do rust (as I found out when some got into my non-skid
on my boat.) It not as bad as ordinary steel wool, but it was a
problem, particularly when I bought it specifically to avoid rust on
my boat(s). I suspect SS wool is not marine grade such as 316 and
304, the two most common types on boats...they have different
purposes, but I forget what the differences and uses are for each one.

I haven't had a problem with bronze wool on a boat, but I think I'll
stick to emery or scotch brite for my antenna...the 2nd next to do on
my list.

Jon W3JT


On Wed, 29 Apr 2009 10:37:21 -0400, Michael Coslo
wrote:

Jim Lux wrote:
lagagnon wrote:
I am about to refurbish an old Hy-Gain TH3-Mk3 Thunderbird tri-band
yagi. This yagi has been used in a coastal environment and thus the
aluminum is slightly pitted and most of the connecting hardware needs
replacing.

I figure steel wool would work fine for the aluminum tubing,

Avoid steel wool. Inevitably, it will leave little iron/steel fibers
behind, which will rust/corrode/react with the aluminum.

Hi Jim,

I keep hearing about steel wool rusting in/corroding Aluminum, but does
anyone have actual evidence? I've been looking on the web, and although
apparently using steel wool on AL will cause warts, bad breath, and the
downfall of the free world, all I've found is admonitions not to use it.
Maybe I'll try an experiment - I have some old antenna tubing.

There's just something a little strange about this. For the steel
particles to corrode the AL, they would have to detach, (easy enough)
settle into pores in the Aluminum at sizes small enough to do that,
(hmmm, those are pretty tiny steel particles) or have some odd property
of sticking to the AL despite cleaning. Then I guess it's a race between
rust and galvanic corrosion?


Use synthetic scrubbies (3M ScotchBrite) instead.

Bronze or stainless steel wool might be a good material to use. Boaters
use it on aluminum.

- 73 de Mike N3LI -

"Michael Coslo" wrote in message
...
Then I guess it's a race between rust and galvanic corrosion?

The aluminum will prevent the steel from rusting at the expense of its
own corrosion.

Use synthetic scrubbies (3M ScotchBrite) instead.

Bronze or stainless steel wool might be a good material to use.
Boaters use it on aluminum.

Because boaters do not understand corrosion and electrochemical
reactions, they often choose poor materials. Brass is more cathodic than
steel, the 400 grade ferritic and martensitic stainless steels are more
cathodic than brass, the 300 grade austenitic stainless steels are more
cathodic than the 400 grades, and precipitation hardenable stainless
steels like 17-4PH lie between 300 and 400 grade stainless in being
cathodic. The more anodic a material is, the faster it corrodes. The
more cathodic (or noble) a metal is, the slower it corrodes.

As I said earlier, I have several good, introductory articles on
corrosion and galvanic series that I can send upon request by email.

--
73, Dr. Barry L. Ornitz WA4VZQ

On Thu, 30 Apr 2009 00:41:21 -0400, "Dr. Barry L. Ornitz"
wrote:

"Michael Coslo" wrote in message
...
Then I guess it's a race between rust and galvanic corrosion?

The aluminum will prevent the steel from rusting at the expense of its
own corrosion.

Use synthetic scrubbies (3M ScotchBrite) instead.

Bronze or stainless steel wool might be a good material to use.
Boaters use it on aluminum.

Because boaters do not understand corrosion and electrochemical
reactions, they often choose poor materials. Brass is more cathodic than
steel, the 400 grade ferritic and martensitic stainless steels are more
cathodic than brass, the 300 grade austenitic stainless steels are more
cathodic than the 400 grades, and precipitation hardenable stainless
steels like 17-4PH lie between 300 and 400 grade stainless in being
cathodic. The more anodic a material is, the faster it corrodes. The
more cathodic (or noble) a metal is, the slower it corrodes.

As I said earlier, I have several good, introductory articles on
corrosion and galvanic series that I can send upon request by email.

As I discovered when I did a restoration and rebuild on my sailboat
about 10 years ago. All of the original interior woodwork fittings on
the boat were held in place by decorative brass screws. As the boat
was built in 1971, but the time I got to it in the late 90's all the
brass screws had "zincified" (probably not the correct term to a
metallurgist, but one that appears in boating literature). This
results in the screws having a pinkish color and they become
very brittle. Any attempt at removing them resulted in the head
breaking off or the Philips cross slot stripping out. I had to remove
all of these with a screw removal tool. They were all replaced with
coated SS screws, the coating for decorative purposes.

At least among sailboaters, who for some reason appear to be more
technically savvy than power boaters, galvanic corrosion is pretty
well understood at least at a layman's level. Most boat repair books
mention this and include the galvanic series and the relative
"nobility" of various metals and alloys. Those of us who sail in salt
water are also well aware of the need to put sacrificial zincs on our
boats to prevent damage to other metal parts. Replacing these is a
regular part of our annual maintenance.

A very high percentage of sailboaters are also hams, far beyond our
normal density in the overall population.


Jon W3JT

Dr. Barry L. Ornitz wrote:
"Michael Coslo" wrote in message
...
Then I guess it's a race between rust and galvanic corrosion?

The aluminum will prevent the steel from rusting at the expense of its
own corrosion.

Use synthetic scrubbies (3M ScotchBrite) instead.
Bronze or stainless steel wool might be a good material to use.
Boaters use it on aluminum.

Because boaters do not understand corrosion and electrochemical
reactions, they often choose poor materials. Brass is more cathodic than
steel, the 400 grade ferritic and martensitic stainless steels are more
cathodic than brass, the 300 grade austenitic stainless steels are more
cathodic than the 400 grades, and precipitation hardenable stainless
steels like 17-4PH lie between 300 and 400 grade stainless in being
cathodic. The more anodic a material is, the faster it corrodes. The
more cathodic (or noble) a metal is, the slower it corrodes.

As I said earlier, I have several good, introductory articles on
corrosion and galvanic series that I can send upon request by email.

I'd be interested. I'm one of those folks who post an actual address in
the newsgroup, so if you would be so kind. Thanks in advance...

- 73 de Mike N3LI -

On Tue, 28 Apr 2009 12:43:59 -0700 (PDT), lagagnon
wrote:

I am about to refurbish an old Hy-Gain TH3-Mk3 Thunderbird tri-band
yagi. This yagi has been used in a coastal environment and thus the
aluminum is slightly pitted and most of the connecting hardware needs
replacing.

I figure steel wool would work fine for the aluminum tubing, I know
how to test the traps, but I am wondering whether to use stainless
steel or galvanized hardware? Which would react least over time with
the aluminum? Also, I remember many years ago there is an electrical
joint compound stuff for using between the tubing sleeves - can anyone
please give me some brand names of this stuff?

Any other ideas appreciated....

Larry VE7EA

I just called Bencher/Butternut about my aluminun vertical and they
suggested NOT using steel wool for cleaning because the residue
of the steel wool rusts very easily. I know this is true from my boat
where we generally use bronze wool to avoid rust. The steel wool sheds
(and I know this from hard experience) as a bear to clean out of
stuff, such as the deck of my boat. The Butternut guy suggest that
rather than steel wool use either emery paper or a Scotchbright pad as
they do not leave residue. Butternut also has a conductive grease that
they provide with their antennas to keep the metal to metal joints
conductive. Steel wool residue can also cause bimetalic corrosion with
aluminum.

Most assuredly use stainless steel fitting and screws. Ordinary
screws/nuts will rust very rabidly. Any boat owner knows that
many so-called compression clamps, allegedly in stainless, do not have
stainless bolts to tighten them. Most of us take a magnet to the
boating store to ensure we got the right things. BTW a boating store
is generally a pretty good place to get stainless steel hardware. They
know that a boat owner will scream bloody murder and besmirch their
reputation if they sell anything but the top quality stuff. We ran one
boating store out of town for selling shoddy stuff.

I'm embarking on exactly the same rebuild on my Butternut vertical so
I just talked to the factory specialist on this very subject just last
week. My spare parts just arrived yesterday. I'm rebuilding because
after 25 years, the wind flexed the tube that mount the antenna, a
vertical, into the ground. I guess that is not too bad service for
this antenna.

Jon Teske, W3JT
Maryland