Rust Pitting?

[Sturwilh]

Hi, I’m new here. I stumbled on this site and it seems you all are pretty knowledgeable so I thought I would ask a question. I have an old trapdoor rifle with some pitting like I haven’t seen on other rifles. There are some deep areas but there is no sign of rust. I was wondering if this pitting might be the result of a deep rust cleaned by electrolysis. Just curious, the rifle is nothing special. I know this question is not specifically trapdoor related but I hope to get into those later. Thank you.

[Dick Hosmer]

Could also have been chemically cleaned with something like Naval Jelly. I'd wipe it occasionally with an oily rag.

[dave]

I would say there is sign of rust, deep in those pits. May not be active rust. Unless pics aren't showing correctly.

[Sunray]

Pitting is the result of rusting. Stop the rusting and the pitting action stops too.

[Sturwilh]

Yes, Naval Jelly, left on too long, is likely the culprit. The pitted areas might have been softer so the acid etched deeper or more probably the Naval Jelly was only applied to those pitted areas. It couldn't be anything else. Looking close, I see no sign of active rust! Thank you

[dave]

You asked for opinions (I thought). I gave mine. I have left naval jelly on over nite and longer, does not make pits deeper but its weak stuff (not like it used to be) and a second coat is usually needed to get at bottom of those pits.0000694.jpg100_0447.jpg Yep, naval jelly and then a polish with Brillo soap pad & hot water! Of course I had no worry about original finish as it was polished to begin with, as you can see.

[Sturwilh]

Dave - The pits have been on this rifle since I've had it and I see no rust deep in the pits. Any naval Jelly used on this rifle was used years ago when it might have been stronger. You did a good job polishing that butt plate but in my case I want to minimize my effects on this rifle. Thanks for the good opinion Dave.

[butlersrangers]

I am not a metallurgist. But, FWIW, I have seen gun parts, especially Springs, ruined by rust removal with Naval Jelly.

I agree with Dick Hosmer that the OP's photo suggests the metal was cleaned with Naval Jelly.

From my limited understanding, I would never use Naval Jelly on gun parts. It contains phosphoric acid, which on certain tempered steels when used for corrosion removal, causes Hydrogen Embrittlement. (A chemical reaction that introduces Hydrogen into tensile steels).

The result to the steel is a loss of ductility. The steel is made brittle and can fail catastrophically by fracture.

I would not use a firearm that shows evidence of 'cleaning' by Naval Jelly in areas requiring great strength.

(A Butt-Plate is one thing, but, a rifle barrel or action components are not places you want steel to fail).

[dave]

Dave - The pits have been on this rifle since I've had it and I see no rust deep in the pits. Any naval Jelly used on this rifle was used years ago when it might have been stronger. You did a good job polishing that butt plate but in my case I want to minimize my effects on this rifle. Thanks for the good opinion Dave.

I did say it may be the pictures but it just looks like dark areas in some of the pits. I did not mean to suggest you do it over with NJ or anything else.

[Dick Hosmer]

The buttplate - while too clean for my taste, was nicely, and carefully, done.

I guess NJ has its' uses, but nothing will make me puke faster than a one-color bright metal surface which is cratered like the moon. I'm just not a big fan of cleaning things to the point where they look new.

[dave]

Well I can agree with that but I like them in condition they would have been while in use with the military, and rust would not have been tolerated in any military. Don't know how they would have cleaned them, probably no need to clean, as they would never get that way to begin with! Same goes for dried grease, dirt, and other crap. Now the picture is of a rifle made from 1924 thru ww11 (1928 on this one), the really old stuff, like trap doors may be a different story.

[Fred]

When I was just a kid, I used Naval Jelly on a Sharps 1874 breechblock. Stupid of me when oil and a stiff tooth brush would've sufficed. I let it sit overnight. The next day, upon rinsing it off, I found that the once smooth breechblock was pitted all over. I mean 100% of the surface.
Naval Jelly has no place in firearms cleaning. Leave it alone. Bad JuJu.

[Dollar Bill]

I am not a metallurgist. But, FWIW, I have seen gun parts, especially Springs, ruined by rust removal with Naval Jelly.

I agree with Dick Hosmer that the OP's photo suggests the metal was cleaned with Naval Jelly.

From my limited understanding, I would never use Naval Jelly on gun parts. It contains phosphoric acid, which on certain tempered steels when used for corrosion removal, causes Hydrogen Embrittlement. (A chemical reaction that introduces Hydrogen into tensile steels).

The result to the steel is a loss of ductility. The steel is made brittle and can fail catastrophically by fracture.

I would not use a firearm that shows evidence of 'cleaning' by Naval Jelly in areas requiring great strength.

(A Butt-Plate is one thing, but, a rifle barrel or action components are not places you want steel to fail).

While hydrogen embrittlement is real, the effect is very localized if done correctly. I've had to perform corrosion removal on high strength steel parts (AH64 main rotor drive plates) and had this discussion with the Boeing and AMCOM engineers. I used straight phosphoric acid applied with a Q-tip and rinsed after 15 minutes. Re-inspect for corrosion and reapply as necessary but limit the time to 15 minutes.

What was funny was the recommended restoration of the rust resistant coating on that part was the use of Birchwood Casey cold bluing!

[butlersrangers]

Thanks Fred and Dollar Bill for your insights and experiences.

I have seen antique gun parts where the metal looked like it went through a fire, although the intact wood told otherwise. The metal was eroded to the point that you could see the 'grain' of how the metal parts were forged. The metal was left 'ashen' and brittle.

I have assumed the parts were cleaned by the misuse of Naval Jelly. (I think possibly a bubbling chemical reaction allowed hydrogen atoms to replace oxygen atoms in the steel)? I am just trying to understand the process and potential danger.