Rust on stainless steel revolver

Good grief. Dunk it in some EvapoRust for a few hours and rust will be gone. EvapoRust is NOT an acid so it won't etch the stainless finish. I would not use any form of abrasive on the finish. If your gun has that nice satin factory finish, It will be ruined. Steel wool is "harder" than stainless steel so it will leave scratches. Maybe bronze wool would be ok though.
 
Just to be difficult, I'll argue that all rust is surface rust as that's where it has to begin. The internal portion of the steel is not exposed to oxygen and humidity, so it can't start there. Nor can it start spontaneously on exposed iron if the relative humidity is below about 30-40%. Even at 50% it has a hard time initiating. This is why old guns and car parts found in Arizona are often in good condition as compared to what you see here. Most folks think the difference is lack of road salt, but even salt needs a minimum of 68% RH to accelerate rusting by activating the iron or steel surface with chlorine ions.

There is a good article on rust in the Wikipedia.

I agree that Evaporust and Rust Release, both of which remove rust by chelation of the iron in it, are good methods of removing rust, but citric acid will also passivate the stainless steel. It does this not by removing carbon, as suggested earlier, but by eating away both rust and any iron on the surface that does not have a chromium oxide protective layer over it. That layer is what makes steel stainless, and by removing all unprotected iron, there is nothing available to rust. That's what passivation is; removing reactants available for chemical activity (reactions that form products, like rust).
 
Just to be difficult, I'll argue that all rust is surface rust as that's where it has to begin. The internal portion of the steel is not exposed to oxygen and humidity, so it can't start there.
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Yes, it starts on the surface. However, my point is, despite people minimizing minor rust on a guns surface by seeming to imply that it can just be removed and the gun is as good as new (because it is just, surface rust), if any rust is present, there are pits in the surface of the steel and there always will be.
 
Here in Florida, I will promise you stainless steel guns will rust. Usually starts under wood grips that aren't sealed. Wood soaks up moisture from humid air and holds it next to the metal.
 
Yes. RH is key. Here is a graph of surface rusting activity in steel:

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Unclenick, the corrosion resistance/rate of steels varies considerably, both among the various stainless steels and among the various non-stainless steels. Do you know what steel alloy was used to develop the graph you posted?
 
IIRC, it was A992 hot rolled I-beam steel, as it was in the context of dehumidifying sandblasting air on its way toward taking rust off bridge steel.

You are correct the rate will vary considerably, but the shape of the graph should apply proportionally. The important point is low humidity stops rust from initiating. This was also discovered by the U.S. Bureau of mines when they worked out that potassium salt in primer residue is what caused rust in gun barrels back in the 1920s (well, worked it out for Americans; the Swiss had figured it out nearly 20 years earlier, but back in those days publications didn't circulate worldwide very well).
 
Unclenick said:
You are correct the rate will vary considerably, but the shape of the graph should apply proportionally.
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As far as common firearm steels, that might be true. 416 seems to be the most common stainless steel used in firearms and it is not among the most stain (rust) resistant stainless steels. But I'm not sure the graph would apply proportionally for all steels.

Some stainless steels will fend off significant rust for a very long time, even under condensing or submerged conditions. Those highly rust resistant stainless steels may be suitable for some firearm parts, but may not be practical or appropriate for others like barrels or actions.
 
Oh, I meant rustable steels. I wouldn't expect it to apply to stainless steels at all. I've never seen uniform rust on stainless of any kind. To rust, stainless has to have iron without chromium oxide shielding exposed or else iron at the surface embedded from an outside source. There's no way to predict how much area that will constitute from one piece to the next as it will vary with its machining and handling history.
 
The welding of certain stainless steels will cause the phenomenon called, "chromium carbide precipitation." I learned that in welding class many years ago.
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When this happens, it changes the properties of the steel. If enough of the chrome in the alloy converts to carbides then there is no longer enough left to provide rust-resistance. One could even say that it is no longer stainless steel when that happens.
 
I think that's right. I read the thread and they were hoping passivation would fix it, but I don't know there'd be enough chromium left or not. My Parkerizing tank was welded up by a fab shop that did some medical work. The welds have never shown a trace of rust, but I don't know if they did anything special to control it beyond just not getting too hot for too long, I don't know. I imagine medical equipment that includes welded stainless pretty much has to be as stainless as possible.
 
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