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Thread: Most Protective Patina Formula for High Carbon Blades??

  1. #1
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    Question Most Protective Patina Formula for High Carbon Blades??


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    I recently had a pretty unsettling experience with one of my most prized custom high carbon blades. I made a stupid mistake and left it outside after I used it to process wood for a fire. It was in its leather sheath for 2 days outside - and it poured the rain both days.. Fortunately, My wife discovered it outside and brought it in. It is O1 steel, and of course was a rusty mess. By the time I got it all cleaned up with WD-40 and ScotchBrite, I discovered a good amount of pitting on the surface of the blade, and of course the edge was gone. It's been sent back to the maker to see what can be done to restore it.

    So needless to say, I am very interested in the most effective method to apply a highly protective patina to my high carbon blades. I know this won't be full-proof protection, but it will definitely be better than nothing. So I've heard of mustard patina, vinegar, lemon juice, etc., and different soak timeframes, but what is the best for corrosion protection? I really don't care about the look or color, etc..

    What is your best patina formula for protecting your high carbon steel blades?

    The reason for my question...
    Last edited by LightGuy; 11-26-2011 at 11:23 PM.

  2. #2
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    Good question. I too am interested in the best protective patina. However, if anyone includes any aesthetic implications to their process, I'd probably play with that too.


  3. #3
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    Patina is caused when the carbon in the steel reacts with an acid (i.e., from food). The patina doesn't really protect against rust. I've found that BreakFree works very well as a rust preventive, and there are lots of other similar products.

  4. #4
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    Even with a patina you will still need a rust inhibitor - Marine Tuf-Cloth from Sentry Solutions is an excellent choice.

  5. #5
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    What makes the patina effective is the fact that it's there. How it's formed has made little difference, in my experience.

    Now, what you put on the blade after the patina is formed can make significant difference. If it's left bare, it will rust just as much as any non-patinated blade. Slower and less aggressively, but it'll rust.

    Coated with an oil of your choice, there will be much less chance for the steel to rust until the coating is disturbed by cutting, wiping or washing it away. A residue generally remains and oils are easy to apply, so no problem there. I like to apply a thin coat of olive oil and then carefully heat the blade several inches above an electric stove burner to hopefully get the oil to adhere better, similar to how cast iron pans are cured, but I'm very careful to not allow the blade to get hot enough to damage it. It may not actually do much, but so far it's worked for me.

    Waxes will stay on a blade a little better than oils, generally. I prefer beeswax if I have to use a wax as it's worked best for me and I don't have to worry about what I cut with my knife.

    The last time I forced a patina on one of my blades, I used about three cups of vinegar in a pot that I heated to just below a simmer (bubbles on the bottom of the pot, but not reaching a boil) until it steamed down to about half it's previous volume. Then, using tongs to hold onto a wad of paper towels, I continuously wiped the blade with the vinegar soaked towels until the blade darkened to a deep, almost black, grey. To stop the acids, I then rinsed the blade in cold, running water and scrubbed it down with a baking soda paste to neutralize any traces of the vinegar acids. The baking soda paste also buffed down the surface leaving a very grey surface that appeared almost parkerized. I then wiped it with olive oil and lightly heated it as previously described. It's only been a few weeks, but so far, so good!

    These are my experiences, anyway. Others will have more or differing information than I do, so hopefully we'll all learn a bit!
    Last edited by Holmesmade; 11-26-2011 at 11:52 PM.

  6. #6
    I've applied several layers of gun blue on the blade of my gayle Bradley. It looks cool and the knife smells like my guns.....

  7. #7
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    ...I used about three cups of vinegar in a pot that I heated to just below a simmer (bubbles on the bottom of the pot, but not reaching a boil) until it steamed down to about half it's previous volume. Then, using tongs to hold onto a wad of paper towels, I continuously wiped the blade with the vinegar soaked towels until the blade darkened to a deep, almost black, grey. To stop the acids, I then rinsed the blade in cold, running water and scrubbed it down with a baking soda paste to neutralize any traces of the vinegar acids. The baking soda paste also buffed down the surface leaving a very grey surface that appeared almost parkerized....
    Interesting way to blacken the otherwise bare blade...I might just try that.

    Have you tried using food grade mineral oil for the blade? Olive oil and other vegetable oils tend to get "gunky" when they dry out...mineral oil is smoother and less viscous.

  8. #8
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    Quote Originally Posted by Gunsnknives View Post
    Interesting way to blacken the otherwise bare blade...I might just try that.

    Have you tried using food grade mineral oil for the blade? Olive oil and other vegetable oils tend to get "gunky" when they dry out...mineral oil is smoother and less viscous.
    I haven't tried mineral oil, mostly because I always have olive oil here for cooking and don't want to spend money to experiment when I'm perfectly happy with this. The way I coat the blade is to wipe on just enough to coat the blade, then heat it as I previously mentioned. Generally, this is done about a guesstimated 8 inches above the stove burner and only so long as my fingers are comfortable. I do a few passes on each side and wipe the blade down with a soft cloth or old towel. I've yet to have anything get gunky or sticky. Even after sitting in a leather sheath for several days.

    This is the one I'm referring to.


  9. #9
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    Mineral oil costs a dollar for a pint. I believe it's what samurai used mixed with a few drops of oil of cloves. Mineral oil works well for me. It's cheap, non toxic and it does the job.

  10. #10
    I can't remember where I read this, but there was a post saying how different acids will react with metal differently. He suggested using Coca Cola to patina your blades with because of the acid (phosphoric acid iirc) would make a more rust-resistant patina compared to one imparted by vinegar.

  11. #11
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    Quote Originally Posted by Fanglekai View Post
    Mineral oil costs a dollar for a pint. I believe it's what samurai used mixed with a few drops of oil of cloves. Mineral oil works well for me. It's cheap, non toxic and it does the job.
    ^ +1.

    I use three oils for my knives, USP mineral oil (mostly), vaseline and beeswax. I don't use olive oil because it becomes tacky over time, mineral oil doesn't.

  12. #12
    My personal carry balisong was patinated with phosphoric acid (sold as rust remover at hardware stores in the Philippines). The only oil I use on my knives is mineral oil: I apply it regularly and it keeps the rust at bay very well.

  13. #13
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    Quote Originally Posted by Fanglekai View Post
    Mineral oil costs a dollar for a pint. I believe it's what samurai used mixed with a few drops of oil of cloves. Mineral oil works well for me. It's cheap, non toxic and it does the job.
    what is the oil of cloves for ?thanks in advance

  14. #14
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    Tip: to help get an even patina, be sure the blade is VERY clean and dry before starting. Wash it with soapy water, rinse with hot water, then towel dry. Then wipe it down with rubbing alcohol and let dry. This will remove all residual oils, even the stuff from your fingers and result in a more consistent coverage of patina, no matter which method you use.

    Personally, I just clean a blade in this manner, then spend time cutting thin slices of apple or potato. Whether forced or gained over time with use, a well patinaed carbon blade is a thing of beauty.

  15. #15
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    Quote Originally Posted by Alberta Ed View Post
    Patina is caused when the carbon in the steel reacts with an acid (i.e., from food). The patina doesn't really protect against rust. I've found that BreakFree works very well as a rust preventive, and there are lots of other similar products.
    Thanks for all the input so far. I didn't think this would start with a debate regarding patina having corrosion protecting qualities. In my 1+ year on this forum I've read numerous posts regarding "protective" patinas, from knife enthusiasts and even knife makers. I've even talked to knife makers at shows who talked about this. I haven't really heard any information to the contrary until now. In searching the web, there is a lot of supporting information on the protecting qualities of patina, and it boils down to this: a patina protects or passivates metal against against further corrosion. A patina - unlike rust - is solid and seldom shows a tendency to flake. Therefore it stays on and slows further corrosion.

    Is it complete rust protection? Of course not. But, in the event of an unfortunate mishap like I mentioned above, a blade with a good patina will fair somewhat better than a perfectly clean blade with no patina.

    So of course I'll keep using the mineral oil and Tuf Cloth and such (when possible), but I will also be adding a protective patina to my high carbon blades as an additional measure.

    I like the vinegar idea. So just a wipedown, no soak? The info about having a perfectly clean blade is also very helpful. I talked to one maker about coating in mustard and leaving overnight. Has anyone done this?

  16. #16
    You guys are too much. Don't worry about how to "force" it. Just use the knife, keep it clean and the patina will develop all by itself. A good patina will help prevent rust, the same way blueing does. Its a protective coating of oxidation not so different from blueing. Forcing it too quickly doesn't allow the protective oxidation layer to penetrate deeply enought to be effective.
    Keep in mind that different steels will react in different ways. If you worry about little pits and uneven coloring on the blade, either don't buy carbon steel or leave the blade wrapped in oiled paper in a safe. Its going to happen whether you like it or not if you use the blade, its part of the aging process.

  17. #17
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    I have a nice Bruce Culberson that had a mishap like that. It was in my pack and my sigg bottle was not screwed on properly and leaked into my clothing layers without knowing for a couple days this fall. The sheath was soaked.

    Was able to fix the edge but has some character pitting now, it had some patina before from regular use but I think a heavy mustard forced patina is needed. With the pitting, rust will take a lot easier now that the polished finish is compromised.

  18. #18
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    Quote Originally Posted by Arathol View Post
    If you worry about little pits and uneven coloring on the blade, either don't buy carbon steel or leave the blade wrapped in oiled paper in a safe. Its going to happen whether you like it or not if you use the blade, its part of the aging process.
    Thanks for that refreshing dose of sanity. You speak the truth.

    Guys, one way or the other, staining -- or even a little rust or pitting -- isn't that big of a deal. Knock it off with a little steel wool or sand paper, then dry and oil the blade. Light rust will often come off with a little spit and a rubdown from a bandana, or paper towel or whatever.

  19. #19
    I agree that you need to be ready for some change in the blades look over time when owning carbon steel. I have used mustard and ketchup blotted lightly over a cheap mora blade for about 2 hours and it came out great. Gives it a spoted design all over. Putting the blade in potatoes for around an hour does about the same thing giving light grey/blue patina all over. As for the level of protection it provides for the blade itself, hard to say but I have noticed far less spots on my mora after periods of it sitting around since the patina was put on.

  20. #20
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    Quote Originally Posted by Alberta Ed View Post
    Patina is caused when the carbon in the steel reacts with an acid (i.e., from food). The patina doesn't really protect against rust. I've found that BreakFree works very well as a rust preventive, and there are lots of other similar products.
    I agree with Ed. "Patina" is surface corrosion. Patina happens. It isn't clear to me that patina really protects. Oil doesn't just happen, but it does protect.
    Frank R

    ... Still looking for a vorpal blade.
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