Rust Prevention – Part 2
In my quest for a definative answer to corrosion protection in the garage, I contacted a number of corrosion test facilities in the United States. Out of 5 emails, I got one response from one facility. Because the person was so gracious to provide lots of information, I have summarize the finding in my own owrds. In no way is this an endorsement – this is a summary of what was revealed:
This laboratory tested about 28 rust preventive products from a variety of manufacturers and continues to on a regular basis. Excellent performance has been recorded from the following products in long-term exposure testing in Salt Fog, Humidity and Cyclic Accelerated Corrosion Testing (all to approved US standards) when applied to cleaned, bare, cold rolled steel test panels.
Thin, “oil-like” products: WD-40, Corrosion-X, Corrosion-X Aviation, Eezox, Boeshield T9, G96 Gun Treatment
Slightly thicker products with an “apple butter” or “yogurt” consistency, yet much thinner in viscosity than “grease:” Cortec “Bullfrog” Spray, LPS-3
The above recommendations assume that the product will be applied such that a noticeable film of the product remains on the surface of the item to be protected. Some products performed better than others. In strictly a Humidity test, WD-40 was about as good as it gets — some panels exceeded 1000 hrs of exposure without red rust on the panel face. In Salt Fog tests, rust appeared about ten times faster than in humidity. Between one and two weeks, nearly all panels exposed in salt fog were seriously covered in rust, but WD-40, Bullfrog, Corrosion-X/Corrosion-X Aviation, and Eezox were less engulfed than panels coated with the other products.
Personally, I employ WD-40 and Corrosion-X Aviation at home for the “home and garage” uses which you describe in your e-mail, with application of the product(s) to the tool following each use. I use Corrosion-X Aviation exclusively to protect blued carbon steel firearms.
WD-40 contains a proprietary mineral oil cut with a proprietary solvent blend. It’s water-displacing action is what provides rust protection, IMO. Over time, as the solvent flashes off WD-40 will become a gummy, varnish-like residue, somewhat orange in color, and also IMO it is this orange residue that is sometimes confused with rust.
The issue I have with WD-40 is that it is somwhat thin in viscosity and tends to run off vertical surfaces, or be slung off from rotating machinery components due to centrifugal force. A more viscous product tends to provide more protection.
Products with molecular-thin oxygen blockers like Corrosion-X and Eezox tend to do well also. If oxygen can’t get to the metal surface, it can’t oxidize the metal. I have a particular semiauto pistol finished with a manganese phosphate that tended to develop rust in the same areas every three to four months, even using a “gun oil.” I solvent cleaned the gun oil using acetone, then applied Corrosion-X Aviation (same as Corrosion-X, except with a viscosity-building additive) every evening over the course of a week. That was 7 yrs ago, and the rust has yet to reappear.
Again, a big THANK YOU to “Scientist X” for proividing this information!