Corrosion Inhibitor Noalox at Home Depot

[Tony Brock-Fisher]

Well, here goes this thread again.

There's two basicly different kinds of stuff. Noalox, which is a green
greasy looking stuff that can be obtained from electrical supply houses
(and Home Depot). The the other stuff is usually bronze- or copper-colored
grease with lots of metal particles in it. Sometimes called Penetrox,
it's available from KLM, Radioware, sometimes HRO (if they have it in stock).

They have two different approaches to the same problem. The problem is 
keeping a good electrical contact in the face of adverse environmental
conditions, usually when aluminum is one or both of the conductors involved.

Noalox works by excluding air and moisture from the joint, in an effort
to prevent corrosion from occuring. I think this stuff was designed
for house wiring, NOT antennas.

Penetrox works by doing what Noalaox does, but in addition, it contains
metal particles of specific metal alloys and particle sizes which are designed
to 'bite through' any oxide layer into virgin metal underneath and provide
good conductivity through the joint.

There are favorite opinions on each. Some users have found that after
a season or two, the joints made with Penetrox have turned all green and
crappy looking (technical term). This makes some people distrust/dislike
the Penetrox stuff. What I have found is that any Penetrox left outside
the joint will do this. The grease base washes away in sun/rain, and the
metal that's left corrodes. But I don't care about stuff outside the joint,
it's the stuff INSIDE the joint that counts. And every joint I've taken
apart that was originally assembled with Penetrox is still greasy/coppery
looking in the area where the contact was made. BTW, KLM is very specific
in their instructions that you should wipe off any excess Penetrox after
the joint is assembled. And don't get it on your clothes!

I think each compound has it's specific uses. I don't think if you put an
ohmeter in Noalox, you would read any conductivity. I think with Penetrox,
you would. I think both will serve to exclude moisture and air. I think
Noalox will not improve the conductivity of a joint over clean, dry
metal-to-metal contact; I think Penetrox would improve the conductivity
over an untreated joint.

I have both, I use both. For antennas, I use Penetrox. I used Noalox once
in a homemade plumbing-style hardline connector, where I didn't want
any conductive metal filings in a small space.

Neither is a panacea. For good results, use the proper goop for the job and
make the joint as tight and stable as possible. For better results,
test, inspect, and rebuild all antennas/joints as necessary for your
environmental conditions...

-Tony, K1KP, fisher@hp-and2.an.hp.com

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