Modern rust preventives are similar to today's hi-tech, chemical gun solvents - no single product is perfect (or best) for all conditions, all the time. If you do a lot of shooting and cleaning, I'm sure you'll agree not all solvents are created equal. Some stomp out powder and carbon fouling with more authority than others, a few work particularly well on lead and copper – still others perform almost magically when it comes time to strip out stubborn wad fouling from a smoothbore.
Likewise, rust preventives are tailored to meet or exceed specific criteria established by the individual manufacturer. A good majority of them are multi-purpose formulas designed to lubricate and/or clean and condition in addition to fighting rust. Products with large percentages of lubricating and cleaning additives may or may not perform to your required level of corrosion protection.
On the other hand, products providing maximum corrosion-resistance may be too messy or difficult to remove for daily use. Understanding these properties is a must in order to select products that meet or exceed your particular application.
To help put things into perspective, let's compare two, very real scenarios. Nowadays, it's not uncommon for large stores, such Scheels and Cabela's, to practice a "help yourself" or "browse at will" policy that permits customers to "pick-up and fondle", leaving behind the remnants of sweaty, acidic fingerprints on every gun they touch. I'd like to believe most shops wipe down their inventory on occasion, but to assume this happens on a daily basis teeters on absurd. Obviously, this situation requires at least a medium-duty, rust preventive that guards against rust caused by daily handling for a full workweek or so. On the contrary, an antique arms collector, who keeps his priceless heirlooms in a humidity-controlled gun safe, and handles them only once or twice a year, can probably get by with something less protective, less messy, maybe even less expensive.
Developing A Test
Brainstorming for this months' Cleaning Clinic generated some interesting thoughts, opinions and speculation from some of our techs and other crew here at Brownells. Summed up, there appears to be an enigma surrounding the performance of different types of rust preventives. What works well for some shooters, could very well fall short for others. So, I felt the best way to assist you with product selection was to try and show the limitations of some of the more common products by subjecting them to a simple 72-hour, environmental test. Since I probably have more in common with Dr. Frankenstein than an Ivy League science graduate, I knew the toughest job would be keeping the test realistic, achieving some identifiable results, and not going too overboard with it. This is what I came up with.
I began by selecting ten products commonly used to protect firearms from rust and corrosion. These were: Birchwood Casey Sheath, Boeshield T-9, Break-Free LP, Break-Free Weapon Wipes, Brownells Cosmoline, Brownells Rust Preventive No. 2, Hoppe's Lubricating Oil, Rig Universal Grease, and Tetra Gun Lubricant. To curb my own curiosity, I also threw in a couple extra lubricants – Valvoline 5W-30 motor oil and the universally recognized WD-40.
The test-bed would consist of 1/8" thick, raw, flat steel plate cut into individual pieces measuring about 5" to 6" long x 1¾" wide. In order to achieve accurate results, each test-bed would need to be as consistent as possible, so I bead blasted the plates to a uniform surface texture. This process removed any pre-existing corrosion and exposed a fresh, unadulterated test surface so every sample would start on the same playing field. Bead blasting also produced millions of microscopic pockets in the metal that would help capture moisture and accelerate rust formation on what would otherwise be a smooth, polished finish.
Starting with the letter "A," I then hand stamped each plate with an identification letter to prevent mix-up during the three day testing process. Plate "A" would be the designated CONTROL plate, left untreated to weather the storm without the protection of any rust preventive whatsoever.
Applying The Test Samples
After designing and printing-out a datasheet, it was time to get down to business and kick-off the study. I wrote "CONTROL" next to the letter "A" on the datasheet and moved the plate stamped "A" temporarily off to the side; then, proceeded to record the name of each product next to one of the remaining letters ("B" through "L") on the datasheet. I made sure to check the datasheet twice just to be sure everything was correct.
Since it's not unusual to use rust preventives on a daily basis, especially if you shoot a lot or carry a concealed weapon, I do consider ease of application and odor to be important factors in the selection process. Therefore, I established a crude, four-level scale for rating sample thickness (or weight). These were: ultra-thin, thin, thick and heavy. Odor would be rated on a numerical scale of 1 to 5, one being no detectable odor and five being knock-your-socks-off, wife-kicks-you-out-of-the-house stinky!
To avoid contamination factors, each test plate was thoroughly degreased with its own, clean rag saturated with Brownells TCE Cleaner Degreaser, then allowed to dry completely prior to applying the rust preventives.
Each sample, with the exception of Break-Free Weapon Wipes, was applied to its respective test plate with a fresh, cotton bore patch to prevent cross-contamination. Weapon Wipes are pre-saturated cloths ready for use, so transferring the product to a patch was not necessary. Since the fluid consistency of the samples varied, I applied them with the mindset that I was protecting a firearm for six months of indoor storage, be it a cabinet or humidity-controlled gun safe. This meant one, even, easy to apply layer on the front face and edges of the plate – no puddling or extra thick coverage was allowed.
Let The Testing Begin
All test plates were positioned flat, sample side up and spaced approximately 2" apart on an unprotected picnic table in my backyard for three days. If you're at all familiar with weather in the Midwest, you know it's not uncommon to experience two or three seasons of weather in a single weekend -– this particular 72-hour period was no exception. We had high humidity, scorching heat, followed by some horrific thunderstorms that produced pounding rains and cool evening temperatures – perfect conditions to grow some serious rust and corrosion on raw steel!
The test plates were inspected at around 24 hours into the study with negligible results, but by day three, things had shaped up nicely.
After 72 hours of exposure, all test plates were brought indoors for evaluation and photographing. You will notice there are two photographs per plate. The first photograph shows the plate immediately after testing. The second depicts the same plate after degreasing with TCE to remove all loose corrosion. It provides the more accurate representation of overall protection. Note that raw steel is especially susceptible to corrosion and is not a true indication of how blued, parkerized, plated or painted gunmetal will react to different environmental conditions.