"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 -

"lagagnon" wrote in message
...
.... 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?
Larry VE7EA

Penetrox P8a from Burndy (Framatome)
Sells in 8.5 Oz. squeeze bottels.
Last for years in a ham's toolbox.

Larry VE7EA[/quote]

here is where to get the grease AMAZON.COM (( GB OX GARD ))
and if you have the vintage Cushcraft A3.i can send you a printable email for this antenna
IF YOU HAVE THE MODEL WITH THE BN-86 BALUN OR NEED IT ORDER# 242
from MFJ.COM
73 N4VGY

here is where to get the grease AMAZON.COM (( GB OX GARD ))
and if you have the vintage Cushcraft A3.i can send you a printable email for this antenna
IF YOU HAVE THE MODEL WITH THE BN-86 BALUN OR NEED IT ORDER# 242
from MFJ.COM
73 N4VGY[/quote]

A old Hy Gain antenna should have been anodized, hence when you clean the corrosion off it, you also remove the anodize finish which will make it corrode even faster.
I guess the key would be to use all stainless steel hardware and fastners when you first assemble it - that way the only thing you have to contend with is the aluminum - which should last forever - as long as you keep the bugs out of the tubing.

I have a old TET antenna out in the garage that had carbon steel hardware and plastic insulators. The carbon steel rusted and corroded and split the plastic hardware and had to be cut apart to move it from it's previous location.

The owner thought that someone would just walk over and carry it home with them. But with each element of the beam being about 36' long - it would have been impossible to haul on the roof of a truck and I had to bring it home 100 miles.
When my tower gets set up, I will order all new stainless steel hardware - which will probably be worth more then the whole antenna when it was new!

Probably the best thing to do with a old antenna is to donate it to the less fortunate and buy a new one!