Rust Prevention: Testing Corrosion Inhibitors

There are a few really good tests of rust protection on the web. I thought
I’d try a smaller study with some of the “winners” from those tests as well as
a few I had laying around. I cut out individual coupons of mild steel and
sanded them bright.


Rust prevention products


Next each piece was degreased with acetone. Gloves were worn for degreasing,
and from that point on, no hands will touch the test coupons.

Each piece was then coated with a different rust preventative. Coatings were
applied by saturating a patch with the preservative, then wiping it on the
coupon. A new set of gloves and patch were used with each preservative, so
there is no cross-contamination.

The pieces will now undergo cycles of exposure to the elements and periods in
my mostly unheated shop. (A few degrees warmer than outside and dry.) To
start with the coupons were left in the rain for 15 minutes.

A bare steel coupon was added about 20 minutes late, so it’s receiving
near-identical treatment, but not in time for the pics.

The pieces will remain on a shop towel, which will preserve moisture. At some
point I will check the backsides as well, but for now we’ll just monitor the

Preservatives under test are:

CRC 350
CRC 400
LPS 23
Renaissance Wax
EWL (Enhanced Weapons Lube – coupon marked “AWL” – oops!)
Lucas Gun Oil
Weapon Shield
Eezox (winner of one on-line test)
Hornady One-Shot (winner of the most comprehensive-appearing online test)

Grading will be as objective as I can make it. Certainly there will be a
definitive 100% for a coupon exhibiting no rust. The first bit of genuine
(orange) rust will eliminate a “competitor”.

The following chronicles some of the events, and my reactions as they occured.
I’m trying to keep it brief, but there were a few surprises, and much
learning, for me.

Ren Wax starts to fail
I had anticipated that the waxy compounds would be impervious to moisture, so
it was with considerable surprise that I observed that Renaissance Wax was the
first coupon to exhibit rust. Even before the untreated metal. This would
seem to imply some randomness as to what rusts, even under conditions as
identical as I could make them. Another theory might be that something in Ren
Wax causes rusting under these conditions, but I am not inclined to believe
that. It could also be a matter of application, but I was pretty careful and
if application played a role, then it would likely do so in practical use as
well. Further, if the rust had appeared only at the edge of the coupon (where
application might be more of an issue) I might consider the result somewhat
skewed, but rust is forming well inside the boundary. At this point, the rust
is light.

Eventually the untreated piece starts to rust, by which time the Ren Wax piece
is well endowed with rust. If you’re noticing the spot on the SP400 coupon,
you might think that’s rust, but it’s a bit of leaf or something.

Again to my surprise (since it had done so well in someone else’s online test)
the Hornady One-Shot was the next to succumb to corrosion.

Here’s the test at 26 days. That’s Ren Wax rusting away at third from the
left in the top row. In the middle of the second row Lucas Gun Oil has sadly
been defeated (I really like this as a lube, and hoped it would do better.)
In the third row, Hornady is racing to corrode as badly as Ren Wax and the
bare steel. The others are (kinda*) unaffected.

At this point you may have noticed a ‘tinge’, a hint of corrosion on some of
the pieces that I have not counted out. This was not at all obvious to the
naked eye, but certainly came to light in many of my photos (if only I’d
looked at them sooner!) as well as when examining under magnification. I
wasn’t paying close enough attention this time ’round to take note of that in
a ‘fair’ way, so I’m discounting it here, but it certainly informs me of what
to look for in my next rust test. For now, we’re only comparing ‘orange’

Another surprise was how well Ballistol held up. I didn’t expect much (I
couldn’t tell you why I had low expectations), but it finally succumbed on day

In the final assessment, here’s the ‘top’ view. Bare steel, Ren Wax, Hornady
One-Shot, and Lucas Gun Oil all gave in. Ballistol did as well, but to a much
lesser extent.

Weaponshield, EWL, and Eezox all held up pretty well, but exhibited that
tell-tale “pre-rust” that I’m not really counting.

The CRC SP350 and SP400 and LPS-3 all looked ‘perfect’ on top.

Then it was time to flip them over, and see how the side in relatively
constant contact with moisture did…

Bare steel failed horribly. Ren Wax faired a little better than One-Shot,
Lucas Gun Oil did a little better. Ballistol wasn’t great, but wasn’t the
loser, and Eezox did pretty well.

Weapon Shield and EWL were pretty much failures on the backside.

In a final bit of distinction, the CRC SP-350 failed, though not as bad as
most, while the SP-400 was a standout in being seemingly impervious to

The LPS-3 came in second, but it had some corrosion starting.

I’m going to chalk this up as a data point, but the biggest lesson, to me, was
probably in how to better test rust prevention next time. (And, yes, there’s
a “next time” in the works.)

First, I think vertically orienting the samples will help to show what
‘creeps’ and what doesn’t. Second, I need to accelerate the test or this will
take months. Third, I need to inspect more closely. The “pre-rust” marks which
should be accounted for, but accounted for differently than “full rust”. I
say this because I think I noticed a difference in the amount of time it took
some of the samples to develop “full rust” after demonstrating “pre rust”. So
although neither are desirable, I think it’s valid to say that something that
delays “full rust” longer than another thing is a better corrosion inhibitor.

It’s also worth noting which compounds are lubricants and which are
exclusively corrosion inhibitors.


My first recommendation is that you run a test yourself! The more the
merrier, and the more data we gunowners have, the better we can decide what to

For my part, and for the moment, I’ll be using CRC-SP400 for all the places
that don’t get handled or require lubricity (e.g. metal under the stock) as
well as for long-term storage.

I like Ballistol for its low odor and low toxicity, so I’ll probably use that
on my regular use firearms, even though it wasn’t the top performer.

I haven’t tried EWL, Eezox, or WeaponShield on any of my firearms for use, but
each have earned a trial, so I will be using them in the future. I’m probably
going to try out SP-350 as a lube as well. (SP-350 is lubricious, SP-400 is

I’ll be testing all of these again, but for the time being I won’t be using
Rennaisance Wax, Hornady One-Shot, or Lucas Gun Oil for corrosion protection.
(Which is a crying shame, because I have had some indication that Lucas was a
superior lubricant to those that I have tried.)

All of that leads to a reminder: this is only a test of corrosion resistance.
I made no attempt to judge lubricity, cost, attraction of dirt, or anything
other than corrosion resistance, so it would be very premature to say that X
is better than Y in general. If I lived in Arizona (someday!) I might be
judging these by a quite different standard. Make sure your choices match
your needs.



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3 Responses to Rust Prevention: Testing Corrosion Inhibitors

  1. Very interesting case study.Amazing article.loved this article. Corrosion is a very a major and serious problem that could make the metal useless.This study of how the corrosion inhibitors works and how much capacity they have to protect the metal from corrosion is amazing.

  2. Bill says:

    Your Hornady One Shot is not the same one tested in the review of 46.
    Yours has a red cap & the highly ranked one from the 46 test has a black cap.
    It’s Hornady One Shot Tab HD-Extreme 99936.

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