How do I stop rusting on my carbon steels?

[LazyOutdoorsman]

My k390 knife has a little bit of a rust problem, even with a thicker coat of mineral oil. Today, I was working outside for a little bit in the humid Florida sun. Naturally, I was drenched in sweat, as well as my knife.
So my question is, what do you use to help prevent rust that holds onto the surface as well as not being super toxic?

[vivi]

I carry salts.

I've found even with oils, waxes etc., carbon steel folders end up requiring more maintenance than salts.

sharpening is a lot faster than taking apart a knife to scrub rust out of liners etc. for me.

The weather is beginning to cool off so I thought I'd get my Police 4 ready to go back into rotation.

I stopped carrying it months ago because I noticed the liners corroding.

Here's what it looks like prior to being cleaned up:

Trade off just isn't worth it for me. I'll take worse edge retention but otherwise zero maintenance over playing that game any more.

[Bolster]

I just recently have been experimenting with "browning," the precursor to "blueing" as is found on weapons. Can easily be done at home, but entails boiling the metal to turn rust (red oxide) into magnetite, which resists rust much better than raw steel. But it does give you a dark brown blade, which you may not like. I'll be writing up my experiments soon and posting in the off-topic section.

EDIT:

viewtopic.php?p=1845851

[RustyIron]

I just recently have been experimenting with "browning," the precursor to "blueing" as is found on modern weapons. Can easily be done at home,

I'll be writing up my experiments soon and posting in the off-topic section.

Cool! I'm eager to see what you're doing. I think browning looks more "authentic" than most "natural" or "contrived" patinas.

[Stirmos]

Get the right tool for the job, a stainless steel knife has serious advantages in such scenarios.

However, I live at the coast and frequently oil and take apart my knives. I also re-apply wax to the actual blade often and keep it clean. It’s just requires a time and place, and sometimes I simply need stainless.
For true carbon steels (1095 etc.), this is not enough to prevent rust. For REX45/REX76/15V/Maxamet it works well and just allows some patina. CruWear/SPY27 stay basically clean this way. And Magnacut/LC200 can do with a lot less efforts, they’re patina free.

[aicolainen]

Get the right tool for the job, a stainless steel knife has serious advantages in such scenarios.

Not what you asked, but what Vivi and Stirmos replied really is the answer.

I had a hard time appreciating carbon steels myself, as they would develop rust very quickly even when only exposed to fresh water and limited amounts of sweat.
Salts were a revelation to me. Less maintenance and way less worrying.

Even though Salts and stainless in general solved my problems, I was kind of bummed not being able to test and experience all those carbon steels people are raving about. I absolutely had to find, or maybe even invent, a use case.
It actually proved top be right in front of me. My work environment is 90+% indoor in climate regulated areas, meaning no water exposure and very low risk of sweating. The remaining >10% as well as getting to and from work is a different story, but even that seems to be within limitations of the non-stainless knives I've tried so far.

I think I've found the perfect balance.
My work, though not what you'll consider "hard work" or blue collar, can be demanding on my knives. I do a lot of unsheathing of electrical cables so my edge touch a lot of solid and braided metal shields. And I cut a fair amount of stubborn zip ties, in hard to reach places, that expose the edge and blade to less than ideal forces in multiple directions. I found that with something like k390 in my work knife I actually have less maintenance and worry less than I did carrying stainless at work.
Pretty much the same benefits that Salts and stainless provides for me in outdoors and sweaty applications.

So it all boils down to selecting the right tool for the job (_{although Dr. Thomas is making his best effort to blur that line}) .

[Flash]

I think for most of people who work a “blue collar” outdoors job like myself require a highly stainless steel knife.
A Carbon steel blade will corrode even with the finest oils just by being in your pocket, because in this part of the world humidity is currently very high and even the slightest form of physical actively has you sweating from every orifice.
I can only speak for myself here but after working and sweating a long shift in the sun, the last thing I want to be doing is maintaining a knife when I get back home.

It’s solely high-stainless folders for me from now on. Magnacut has been particularly good for me - as unfashionable as it is I’m fully still aboard that hype train.

[JoviAl]

Yeah, +1 for Salt knives are the tools for the outdoor job in high humidity.

H2 SE might not be everyone’s cup of tea, but it is hard to beat for an outdoor beater. I’ve tried to make K390 work in the tropics for outdoor work and after a few hundred cuts it would rust in my pocket while I sat and made a brew even though it had a fresh coat of Marine Tuf-Glide on it. A Police 4 LW SE in something mega stainless would be brilliant.

[LazyOutdoorsman]

I just recently have been experimenting with "browning," the precursor to "blueing" as is found on weapons. Can easily be done at home, but entails boiling the metal to turn rust (red oxide) into magnetite, which resists rust much better than raw steel. But it does give you a dark brown blade, which you may not like. I'll be writing up my experiments soon and posting in the off-topic section.

Never heard of that before. I wonder if it damages the temper though

Yeah, +1 for Salt knives are the tools for the outdoor job in high humidity.

H2 SE might not be everyone’s cup of tea, but it is hard to beat for an outdoor beater. I’ve tried to make K390 work in the tropics for outdoor work and after a few hundred cuts it would rust in my pocket while I sat and made a brew even though it had a fresh coat of Marine Tuf-Glide on it. A Police 4 LW SE in something mega stainless would be brilliant.

.

Are there any real downsides to the para 3 lw magnacut SE to your H2 SE? I am kind of interested in a serrated blade for fishing and general stuff.

[LazyOutdoorsman]

I'm excited for the magnamax to drop, something stainless but with the wear resistance of a11 class steels. I hope its not just a s110v where it supposedly only holds a working edge.

[JoviAl]

I just recently have been experimenting with "browning," the precursor to "blueing" as is found on weapons. Can easily be done at home, but entails boiling the metal to turn rust (red oxide) into magnetite, which resists rust much better than raw steel. But it does give you a dark brown blade, which you may not like. I'll be writing up my experiments soon and posting in the off-topic section.

Never heard of that before. I wonder if it damages the temper though

Yeah, +1 for Salt knives are the tools for the outdoor job in high humidity.

H2 SE might not be everyone’s cup of tea, but it is hard to beat for an outdoor beater. I’ve tried to make K390 work in the tropics for outdoor work and after a few hundred cuts it would rust in my pocket while I sat and made a brew even though it had a fresh coat of Marine Tuf-Glide on it. A Police 4 LW SE in something mega stainless would be brilliant.

.

Are there any real downsides to the para 3 lw magnacut SE to your H2 SE? I am kind of interested in a serrated blade for fishing and general stuff.

Only that it isn’t a Jumpmaster 2 joking aside I’m sure it would be a fantastic knife - Magnacut is in my experience as good as the hype

[spydorinox]

I just recently have been experimenting with "browning," the precursor to "blueing" as is found on weapons. Can easily be done at home, but entails boiling the metal to turn rust (red oxide) into magnetite, which resists rust much better than raw steel. But it does give you a dark brown blade, which you may not like. I'll be writing up my experiments soon and posting in the off-topic section.

Never heard of that before. I wonder if it damages the temper though

Yeah, +1 for Salt knives are the tools for the outdoor job in high humidity.

H2 SE might not be everyone’s cup of tea, but it is hard to beat for an outdoor beater. I’ve tried to make K390 work in the tropics for outdoor work and after a few hundred cuts it would rust in my pocket while I sat and made a brew even though it had a fresh coat of Marine Tuf-Glide on it. A Police 4 LW SE in something mega stainless would be brilliant.

.

Are there any real downsides to the para 3 lw magnacut SE to your H2 SE? I am kind of interested in a serrated blade for fishing and general stuff.

I know a few years back Spyderco has claimed H2 SE has the best edge retention of any steel they tested. Not sure exactly how they qualified that. It would be interesting to see some tests of SE Magnacut vs SE H2 (do they exist?).

[LazyOutdoorsman]

I just recently have been experimenting with "browning," the precursor to "blueing" as is found on weapons. Can easily be done at home, but entails boiling the metal to turn rust (red oxide) into magnetite, which resists rust much better than raw steel. But it does give you a dark brown blade, which you may not like. I'll be writing up my experiments soon and posting in the off-topic section.

Never heard of that before. I wonder if it damages the temper though

Yeah, +1 for Salt knives are the tools for the outdoor job in high humidity.

H2 SE might not be everyone’s cup of tea, but it is hard to beat for an outdoor beater. I’ve tried to make K390 work in the tropics for outdoor work and after a few hundred cuts it would rust in my pocket while I sat and made a brew even though it had a fresh coat of Marine Tuf-Glide on it. A Police 4 LW SE in something mega stainless would be brilliant.

.

Are there any real downsides to the para 3 lw magnacut SE to your H2 SE? I am kind of interested in a serrated blade for fishing and general stuff.

I know a few years back Spyderco has claimed H2 SE has the best edge retention of any steel they tested. Not sure exactly how they qualified that. It would be interesting to see some tests of SE Magnacut vs SE H2 (do they exist?).

I heard that too, but logically, SE k390 should far exceed H2 SE.
Now that im thinking about it, I really want to see that data.

[Doc Dan]

For my K390 I keep all exposed metal parts and the pivot area coated with a very light coat of Vaseline. It is paraffin wax and mineral oil and does a really good job. Thiers Issard, the top quality straight razor maker, recommends Vaseline to keep rust away. It is food safe, too.

[LazyOutdoorsman]

For my K390 I keep all exposed metal parts and the pivot area coated with a very light coat of Vaseline. It is paraffin wax and mineral oil and does a really good job. Thiers Issard, the top quality straight razor maker, recommends Vaseline to keep rust away. It is food safe, too.

Thank you, Ill see how much better it performs over my current coat of mineral oil.

[Scandi Grind]

I just recently have been experimenting with "browning," the precursor to "blueing" as is found on weapons. Can easily be done at home, but entails boiling the metal to turn rust (red oxide) into magnetite, which resists rust much better than raw steel. But it does give you a dark brown blade, which you may not like. I'll be writing up my experiments soon and posting in the off-topic section.

Oh, I can't wait to hear about that. I am familiar with the idea because it was used on old black powder rifle barrels and some people believe that is how the British Brown Bess got it's name. I have never heard of the boiling step though, just more of a rust then sand, and repeat type process. Eager to hear about the results.

[toml4185]

A thin coat of mineral oil is good in general. If you expect moisture, don't reach for K390 (and others like it). Get a salt.

[Doc Dan]

For my K390 I keep all exposed metal parts and the pivot area coated with a very light coat of Vaseline. It is paraffin wax and mineral oil and does a really good job. Thiers Issard, the top quality straight razor maker, recommends Vaseline to keep rust away. It is food safe, too.

Thank you, Ill see how much better it performs over my current coat of mineral oil.

It is a lot better because the wax puts a barrier and keeps the oil in place.

[Bolster]

I just recently have been experimenting with "browning,"...

Never heard of that before. I wonder if it damages the temper though

ChatGPT swears it does not, as the boiling is around 212F, which is far below most tempers.

However, somewhere on this forum, I once saw someone post about a steel that actually did use a very lower temper, although I don't recall how low, or what steel it was. But from what I've read, 212F is not a temper-ruining temperature. Generally low tempering ranges are 300-400F, medium tempering ranges 400-480F, and high tempering ranges 480-570F. If I recollect, "super steels" generally are in the higher ranges, no?

I hope to get photos up tomorrow.

[RustyIron]

ChatGPT swears it does not, as the boiling is around 212F, which is far below most tempers.

If the temper is lost if you put it in boiling water, what will happen if you're cooking and cut something hot? But if it's a concern, you can go totally old-school.

I've never done it, but I find it intriguing. In the old days, browning was done with urine or horse manure. I'm not joking. Since you're now our resident browning expert, you should give it a try.