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Stainless & Carbon (Mora)

Discussion in 'Non-Firearm Weapons' started by Bobson, Dec 1, 2018.

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  1. Bobson

    Bobson Member

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    Based on the excellent reputations of the Mora knives that I had frequently read here on THR, I bought two of them about a year ago - one carbon steel blade, and one stainless steel blade. I had read (briefly, not in any tremendous detail) pros and cons about each steel type and figured I’d like to try both. At any rate, I threw both in my BOB and basically forgot about em for the better part of the year.

    To make a long story short, I had the opportunity to use the knives to field dress, skin, and butcher up a whitetail buck about a week ago. Prior to that, both blades were brand new and had never been used to cut anything. Additionally, I had visually inspected both and they both had the appearance of knives that had just been opened from the original package in the past few moments. After the work on the deer (about three-ish hours, it was my first time leading the job), I took both knives in the kitchen and washed them thoroughly with dish soap and water the same way I would with any of my dishes. I noticed the carbon steel blade had a very unique “wear” on it at this point - literally immediately after washing, for lack of better way to put it.

    The same knife was used and washed, again, after a similar but smaller job a few days ago. The following three pictures are the two knives tonight. Blue is the stainless, orange is the carbon steel.

    Is the blade damaged, or is this normal? Do I need to oil this blade? If so what type? Gun oil? Will this “wear” or “patina” or whatever it is damage the blade, or is it purely cosmetic?

    Both knives performed excellently, FWIW. Both need to be sharpened up, but other than that I am extremely pleased.

    Thanks for the help.

    P.S. I know it looks like the orange/carbon steel knife has some gunk at the base of the blade where it meets the handle, but I assure you there is nothing there that can be washed or scraped away. It’s just discoloration on the steel.
     

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    Last edited: Dec 2, 2018
  2. milemaker13

    milemaker13 Member

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    I have that knife in stainless, but have not actually used it yet. Its in the family camping kit.
    I think the carbon one is showing early signs of rust. Yes, it should be oiled as any carbon steel blade should. I think gun oil or similar would be my choice.
     
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  3. JohnKSa

    JohnKSa Moderator Staff Member

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    Is it normal? Yes. Carbon steel oxidizes and rusts.

    Does it damage the knife? It can if it's allowed to progress enough. And it's not really doing the edge any good, even when it hasn't progressed much. Any sort of degradation from oxidation visible on the side of the knife is also happening to the edge, probably moreso since the edge has a lot of surface area for a very small amount of volume.

    To be fair, it's not that hard to prevent a knife from rusting by the application of oil and the prompt removal of anything that gets on the blade that could cause oxidation. Or you could just buy a stainless knife. Barring a very few exotic alloys, "stainless" knives are not completely corrosion proof, but most of the good stainless steel knife alloys are corrosion resistant enough that you really only need to worry about rust due to extreme neglect or serious abuse.

    The three ways an edge is dulled:

    Chipping/rolling--contact with a hard surface breaks or bends the edge.
    Abrasion--contact with an abrasive material wears and rounds the edge.
    Corrosion--Oxidation/rust damages the edge.

    My philosophy is that if I can virtually eliminate the effects of one of the three dulling mechanisms just with a purchase decision, that's a win. My working knives are all stainless steel.

    That said, clean/dry your carbon steel knife if it gets wet or is exposed to acidic materials (e.g. blood, fruit juice, etc.). Keep a light coating of oil on it--preferably something benign if the knife will be used for food prep. With some simple care, it will provide a lifetime of service.
     
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  4. readyeddy

    readyeddy Member

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    My carbon steel mora rusted from 2 days of dried deer blood. Steel wool and soap removed the rust and left a stain. Touched it up with a creramic rod and has given good service since. Stain has been cosmetic and rust has not reappeared for the past three years.
     
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  5. Ramone

    Ramone Member

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    As someone who lives and works in the Marine environment, one of the best hacks I've come across for knives and tools is that plain unscented chapstick is an excellent protectent for carbon steel- cheap, widely available, conveniently packaged.
     
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  6. kBob

    kBob Member

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    For gosh sakes Ramone don't give away all the secrets of plain folks for free. Cheeze, next you will be letting them in on coating hunting knives with a light coat of vasoline!

    -kBob
     
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  7. hso

    hso Moderator Staff Member

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    If you don't protect steel it oxidizes, i.e. rusts. Carbon steel rusts quicker than "stainless". Steel will also stain and carbon steel will stain quicker than stainless.

    You should clean any blade that has blood on it right away and before putting it back in the sheath and after cleaning you should dry and coat it.

    We've had extensive threads on how to protect steel, but the best information was from a thread elsewhere in THR where DIY_guy actually conducted an extensive side by side test. His work showed that our of dozens of products, Hornady One Shot, Frog Lube and WD-40 Corrosion Inhibitor performed best at preventing rust. BTW, here's his picture of carbon steel that has sat out for about EIGHT WEEKS.
    [​IMG]

    I've used Renaissance Wax for years as well as a bike product called White Lightning Clean Ride. They're both wax products that have protected effectively.

    I carry a Marine Tuff Cloth when out to make a quick wipe down to protect steel and it works well also.

    I keep a ZRust emitter in drawers and bags to protect carbon steel while being ignored.

    You can use a lot of common products, but nothing beats these specialty products.
     
    Last edited: Dec 2, 2018
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  8. lemaymiami

    lemaymiami Member

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    I've found as a general proposition that carbon steel holds an edge a bit better than the stainless steel blades (and I have both...). The carbon steel needs a bit more maintenance (oiling after cleaning and sharpening) than the stainless. For me I use the same rag that mops up semi-synthetic oil spills ( when I'm adding oil to the internal tank on my outboard motor) on the carbon steel - then wiping it off with a clean cloth... Since I work around saltwater (understatement) my carbon steel blades stay at home - I keep and use stainless blades around the water...

    Over time the carbon steel blades will darken and get a nice patina - you can rush it, but they'll get that patina from real world use. If I were off the water and never near the salt again - I'd prefer the carbon steel...
     
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  9. Blkhrt13

    Blkhrt13 Member

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    Neither is hurt. A mild patina of rust never killed a blade. Most of my us made old timers carry one about a week after being in my pocket. I can shave with most of the blades on them.
     
  10. mdauben

    mdauben Member

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    Carbon steel blades can develop a grayish surface discoloration known as "patina". Many people like the appearance of patina and actively encourage the development of the discoloration on their non-stainless knives by soaking them in lemon juice or stuck in an apple overnight. Patina itself won't damage the blade or edge.

    That said, carbon steel blades do require a bit of extra care to prevent actual rust. Avoid storing them in leather sheaths. Coat them with a rust preventative like mineral oil or wax in between uses. Dry them thoroughly after expose to wet conditions, especially marine conditions.
     
  11. Elkins45

    Elkins45 Member

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    I like Johnson’s Paste Wax, or mineral oil if it’s going to be used on food. Believe it or it, unsalted lard is also a good choice.
     
  12. Browning

    Browning Member

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    This is what the patina looks like on my oldest Mora.

    IMG_7513.jpg

    35612971884_72ba53edca_o.jpg

    It's ugly because I sanded on the handle until it fit my hand. All the rest are stainless.

    Yours looks like it has some rust beginning. Like others have already said I'd hit that with steel wool and oil and then coat it.
     
  13. Gordon
    • Contributing Member

    Gordon Contributing Member

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    here is a shot of a carbon steel blade of a custom knife Sam1911 made me. I used it to cut brush and cut tritip at a few large barbques and also did the worst you can do to carbon blades- cut fruit with it in orchards, all though blood is very harsh too. It does not affect the sharpness in any way. I rinsed it off within a day of using it at events ect. , I use food grade mineral oil on things I cut food with. This is a rugged duty all purpose blade. I have never found a true stainless, like 440c to cut as well as a properly hardened carbon steel as they lack microscopic "tooth" . Stainless is also harder to keep sharp .
    P1030347_zps9d7050d7.jpg

    I prefer not to have coated blades which eliminate this problem, for a while :)
    P1030346_zps4bf729fd.jpg
     
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  14. Slamfire

    Slamfire Member

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    Use a high carbon steel knife enough times and the surface will develop a thin layer of rust. Some call it "patina", but its rust.

    AvbHWCE.jpg

    It is not the end of the world

    I took a picture of a bud's 1960's Case Canoe. This was a gift to Bud from his Dad, might have been 1964. Bud has carried the knife into the woods, and in fact, had field dressed a deer the weekend before, and had not cleaned the knife. That stringy stuff is from the deer. Yuck!.

    vhYnLb5.jpg

    I was getting a little color change on this Mora, this is the laminated high carbon steel knife

    zzgya1C.jpg

    12C27 is pretty hard to rust, so this Mora still looks shiny

    Y2sXvq5.jpg

    One of these days I am going to have to take pictures of pitted blades. I have obsessive compulsive behaviors about rust, I really, really, flip about about rust on my knives, or much of anything. I lived next to the saltwater in Florida for over a decade, and you know, a salt water environment is the most corrosive environment next to a chemical plant. Nails would rust inside the boards. Electrical wiring rusted, electrical components rusted, computer boards rusted inside the layers. You can't leave anything metal out and wet, and not get corrosion. So, I don't like rust on my knives. Even if the surface is pitted, the edge can be sharpened and the knife will be useable.

    I was at Randall knives Orlando and asked the shop attendants about preventing rust on the high carbon steel Randall that I purchased. Their advice was to go cut tomatoes and develop a patina, and forget about it. Shiny did not cut it with them, sharp edges cut it with them. Patina was just cosmetic.

    Your high carbon knife may rust in the leather sheath if you have a leather sheath. I have a nice Eastwood knife that lightly pitted in the aftermarket sheath. Must have been some strange chemicals used in the leather tanning. If you are really, really, worried about rust, you can oil, or grease, the blade, wrap it in cellophane, and stick in in the sheath. The cellophane and oil will create a barrier.
     
    Last edited: Dec 13, 2018
  15. Speedo66

    Speedo66 Member

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    I bought a stainless Mora fishing knife 40 years or so ago in Sweden for about $7. I used for many years on my boat that was slipped on the Hudson River, which is tidal. Almost every piece of metal brought on that boat rusted, except the Mora. Although the leather sheath eventually fell apart, to this day, not a speck of rust on the knife. Looks like the one below, except mine has smaller, sharper teeth on top.

    Count me as a big fan.




    s-l500.jpg
     
    Last edited: Dec 14, 2018
  16. readyeddy

    readyeddy Member

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    A friend’s dad has a big Bowie shaped knife with a blade that’s about 12” long and maybe 1/2” thick carbon steel. Probably made from a leaf spring. He uses it for yard work and keeps it outdoors. It’s covered with rust from the rain and tropical weather, but that massive blade looks like it will last several lifetimes.
     
  17. sparkyv

    sparkyv Member

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    I have a late 70's or early 80's Canoe, and I am impressed that your bud was able to field dress a deer with it! Cool!
     
  18. hso

    hso Moderator Staff Member

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    Not if the rust keeps eating it. Rust also destroys the edge forcing the user to sharpen it every time they want to cut something instead of smash through.
     
  19. Deltaboy1984

    Deltaboy1984 Member

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    Apple Cider vinegar put 's a nice finish on Carbon Steel ,in about 20-30 minutes!
     
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