Knife patina rusting?

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Xenon

Joined
Jul 1, 2018
Messages
6
Hello all

As you can see I’m new here, (only created this account to get my question answered) and relatively new to knife stuff in general. Recently I purchased a Mora robust with carbon steel, and I decided to try and put a patina on it. I used the apple cider vinegar method and let it sit there for a good 14 hours or so, and took it out occasionally to check up on it and clean it off with rubbing alchohol. It worked relatively well when I checked on it one final time the following morning after initially starting the process, and I cleaned it off and oiled it. However, two lines of what appear to be rust formed on the blade and started to become more visible over time. They’re orange and brown colored and a little bit of purple almost as well. I tried to scrub them off with the baking soda method but it didn’t do anything.

Does anyone know what these lines may be? I’ve asked a few people already and they say it isn’t rust, but I don’t know what else it could be. It’s not rough or anything to the touch,. Is it really part of the patina?

https://imgur.com/gallery/RKShlwM

Please help!?!?!
 
Last edited:
Might I add the lines of “rust” appeared at the very bottom of the blade apparently where the vinegar stopped. That still doesn’t explain atleast to me why it’s rusting or discorlored
 
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That line appears to be the vinegar line, where you filled up the container. 14 hours is a bit much for a vinegar soak. 1-2 hours should do the trick. Right after you pull the knife out of the vinegar, it should be rinsed with cold water and blotted dry. Don't wipe, if you wipe it, it will remove some patina and leave streaks. Once your blade is blotted dry, applying a coat of oil is pretty crucial to protecting against rust. Once the oil is lightly dabbed on, your knife should be good to go.
 
Rubbing alcohol is mostly water. I would wipe it with mineral oil myself. That being said, I'm not a patina fan, so I don't know much about forcing one.
 
So the lines aren’t rust, right? ok that’s a relief. So what do you suggest I do at this point? I have already taken it out of the solution and oiled it a good while ago. Should I just leave it and try to ignore the discolored lines?
 
For a forced vinegar patina, I like to go with HOT vinegar. I heat the vinegar in a tall narrow microwave safe glass (pyrex cup for example) in the microwave until it starts boiling, then take it out (use a potholder or wet dishcloth) and stick the blade into it. It will actually start sizzling. You'll get a good black patina in about 30 seconds.

You can probably get that line off by using more vinegar (heated but not to the point where you'd burn yourself) on a paper towel. Alternately, use some Bar Keepers Friend powder and scrub it off.
 
Do you think if I use the boiling vinegar method it will remove the lines? And with the paper towel method how would you go about doing that, just dribbling hot vinegar on a paper towel and using that to rub it off?
 
After you use vinegar you should neutralize with baking soda.
Then clean and wipe with mineral oil.
 
Xenon said:
just dribbling hot vinegar on a paper towel and using that to rub it off
Click to expand...
Something close to that, yes. From looking at your photo, that line may have occurred because it was where the acid was interacting with the air, so you may have gotten some red iron oxide (produced in the presence of oxygen) versus black oxide, as the vinegar essentially evaporated a little because of the amount of time that passed. Just like getting a knife wet and then wiping it off won't rust, but letting the water sit on the knife (and evaporate) does cause rust.

With a regular patina formed by use over time, new patinas tend to overwrite older ones, which is why I suggested perhaps a fresh vinegar treatment might help. The heat just makes it work faster.

You could always buff or scrub with BKF powder that I mentioned above, or try a metal polish, and then touch up the patina afterwards if you ended up removing too much.

It also looks like it could be a reaction to whatever glue or other residue may have been left by molding the handle onto the blade. Hard to tell.
 
Ok, I did just try the vinegar paper towel method and it made the lines much less noticeable but not completely gone, it also took away that lighter gray line you see below the red ones, making it the same color as the rest of the blade. I then applied oil but I didn’t neutralize it with baking soda. I might try a new vinegar solution eventually. All I care about is that the lines aren’t rust, which they aren’t correct? And that they aren’t too noticeable, which they aren’t at the moment but they might become more noticeable who knows.
 
Xenon,
You’re good bro. Oil it up and don’t sweat it. When you force patina sometimes you get some redness at the edges of the patina. You can either wipe it off or do like you did which is patina the whole thing. Just put some oil on the blade and enjoy.
 
A patina is created when acidic substances (meat, vinegar,citrus) react with the carbon in the steel. The patina itself is not protection against further corrosion. Keeping the steel dry or using a rust preventive (good idea if storing) will help prevent rust.
 
Ok thanks guys, I ended up soaking it in hot ACV one last time which removed the red lines, neutralized it with baking soda and then applied oil. It should be good to go, the only thing I’m unsure about is how good the patina will stand up to use. I’ve heard that the patina will wear off with use, but I don’t know how easily.
 
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