Once a blade begins to rust, does that mean the knife is ruined?

A

Adaam

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Jul 10, 2011
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I'm new to knives and have been looking around for a good, general purpose knife. Originally I was looking at a KA-BAR D2 extreme or Next Generation. I'm also now looking at a Buck 119. However, alot of people are saying 1095 steel or 1095 CV is the best steel you can get. Now, I have never really understood how people can want a steel that will rust so quickly and kind of "punish" you by rusting if you accidentaly leave it for a few days uncleaned or don't dry it properly. I've never really liked knives that can rust either, simply becasue there is the fact that even when you think you've taken care of them, they can rust and I see this as putting your knife at a disadvantage to a stainless knife, and makes it less useful and less of a knife. I feel that it makes the steel itself less useful than a stainless, as it needs to be cared for more to get the same result. Anyway, I'm now also looking at a KA-BAR Becker BK7 or BK9, and some other knives made from 1095. I know the rust can be avoided if I oil the blade, but I have a few questions about the steel and maintenance.

1: Firstly, if you have a non stainless teel knife, made from 1095, and it begins to rust (due to the coating rubbing off or on the edge of the blade) does this mean the blade is screwed? Does the rust, once it starts, quickly etch into the blade and no matter what you do, you can't get rid of it and it will keep coming back, even if the blade is visually clean? I had a pocket knife which rusted, and tried to remove the rust, and oiled it etc. but the rust just kept coming back, so that has led me to believe that once a blade rusts, even lightly, it has set in permanently and no matter what you do it will keep coming back.

2: Doesn't the oil on a blade rub off with use? I know you're supposed to keep a light layer of oil on the blade, but wouldn't it wear off with use and expose the metal?

3: Do you find that the rusting of a 1095 steel is a big problem, or am I just blowing it out of proportion by thinking rust + knife = end of knife, and that rust is one of, if not the biggest problem you can face with a knife. Is it a big deal, or am I just worrying too much about a small problem which I for some reason are too concerned about?

4: Is it easy to recover a rusty 1095 steel blade, and return it to good condition?

5: does rust affect the usability of a knife majorly, and will it eat away at the blade, compromising the strngth and altering the blade by disintegrating it slowly?

I guess what I'm asking in question 1 is if a knife's blade rusts lightly, is the rust like a form of "cancer" that even if you remove the rust visually, it will keep returning (even if you care for the blade properly)? I can't seem to word this the way I want to, but hopefully someone will understand what I'm saying. Can someone please help me and tell me whether I am just worrying about rust too much? Because (I dont know why) I seem to think that if a knife can rust, it's instantly less useful and more delicate than one that can't.
 
Surface rust is not really a big deal, you can clean it off with WD-40 and a green scotchbrite, or any other abrasive/lubricant combination. It doesn't affect the integrity of the steel unless it's left to rust for a very long time. One of the good things(IMHO) about a carbon steel(non-stainless) or coated blade is you can count on it not looking brand new for very long, so you're not afraid to use it.

As for your first two points, the steel under the rust actually forms an oxide layer that is less suceptible(but not impervious*) to rust from that point on. Also, the oil will rub off. Some oils/lubricants/protectants will stay on longer than others, but they will all need to be reapplied eventually if you are using the knife.

Another thing -- 1095 is not the best steel you can get, there are many more steels with better specs in one way or another. 1095 is however a very good steel due to it's ability to sharpen easily and hold that edge reasonably well. I think you'll find the hunt for the perfect steel is just going to run you around in circles. All steel will rust(yeah, yeah, I know. H1 *sigh*), it just happens slower with stainless.

When you're done with you knife, just scrub off the gunk, oil it up and don't store it in leather.

Kabar's 1095 cro-van is highly regarded around here, as you seem to have already discovered. With a small amount of care, there are few reasons to shy away from a carbon steel blade.

*Wait 'til you learn about patinas. ;)
 
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Well, let's take that one question at a time:

1: No. Even severe rust with significant pitting can be chemically removed and neutralized (naval jelly, etc). MOST corrosion is of the "surface rust" kind, and can be safely removed with just a little bit of time and elbow grease. After it's removed, a light coating of oil will prevent the rust's return. I am not sure what happened to your other blade.

2: Any protectant will slowly rub away and need to be renewed, some will stay around longer. Eezox is my personal choice for my non-stainless blades, it is an evaporating, dry-film corrosion inhibitor that tends to stay around fairly well. *EDIT* It's NOT food-safe, though. For food-contact knives, mineral oil regularly applied is still the best option.

3: Nope, I've never had a problem with it at all. Rust isn't the end of the world, just a minor maintainence issue. You have to really ignore it for a LONG time to get any significant amount of pitting, and the minor surface oxides that might form from a wet weekend of camping, leaving it out in the rain, etc are easily removed.

4: Depends on HOW rusty, but unless the pitting is so severe that the blade itself is too weak to support the cutting edge, it's just a matter of the time it takes to expunge the active rust.

5: No. Unless you let it progress for a LONG time, it's not a problem. There is no 'cancerous' rust that will keep returning despite your best efforts, it's a surface condition only that just needs some periodic mainteinence to keep at bay. Think of all the museums that have swords and other blades from the middle ages. They didn't have stainless steel then, and didn't even have good, modern corrosion protection agents!

I think you're worrying a bit too much about it, as long as you take moderate care of your blade you'll never even see rust poke it's head up. If there's some kind of problem (Oops, left that knife outside over a rainy night), in my experience it's not that big of a deal to remove. Grab one, and don't look back. Think of all the Samurai who's blades are STILL family or state treasures. They didn't have a rust problem. :)
 
It doesn't mean that the blade is toast. Most straight razors are made of carbon steel, and they get rusting all the time. They're still very usable.
 
As has been pointed out, a little surface rust is no big deal. Moisture, salts (chlorides), and acids are the main culprits. The salts come from things like food, blood, and finger oils that get left on the steel. The acids often come from food (fruit, in particular) or chemicals. Keeping the blade clean & dry, after use, is the best way to prevent about 99.9% of the problem. The 'red rust' is a type of iron oxide that, when formed, occupies more physical space than the individual elements which make up the steel, which is why pitting occurs. The 'black oxide' (patina) that forms in 'healthy' conditions (iron in the presence of oxygen), doesn't displace surrounding steel in such a way. It just forms in a very thin layer at the surface, which basically halts the oxidation process and protects the steel underneath.

Removing light surface rust is just a matter of scrubbing or sanding it off, most of the time. There are chemical means to remove it also, but you have to be careful with those. They're usually more corrosive than what caused the rust in the first place, so immediately and completely cleaning them off (neutralizing), after use, is paramount. The 'clean' steel underneath the surface rust is just as healthy as ever, so you have no worries there. Oiling or otherwise chemically protecting the steel can help, but ONLY IF the steel underneath is completely clean & dry beforehand. Otherwise, whatever 'protection' you apply will just trap those harmful things against the steel, which will then continue to rust.

Even dust particles can absorb moisture/chemicals/etc. It's a pretty common problem, when a dirty/dusty rag is used to oil a blade, for the dirt & dust to transfer from the rag, getting 'stuck' to the blade with the oil, and create a bigger problem by trapping moisture or chemicals against the steel. Small pits will form under every particle trapped in such a way. Moral of the story, apply oil with a CLEAN cloth (even better, a new paper towel is probably the safest bet).
 
Never too sharp-

I would be careful using the green scotch brite pads. Some of them have silicon carbide abrasive in the matrix.

I noticed some scratches on a car window that I had scrubbed some bird stuff off. This is from the McMasterCarr Web site:

"Nylon mesh abrasives are used mainly as surface finishing products. They change the work surface without removing or damaging the base material. You can use them as an alternative to wire brushes, steel wool, sandblasting, buffs and compounds, rubber bonded abrasives, and sandpaper.

Also known as nonwoven abrasives, they are made of abrasive grain and nylon fibers. Flexibility depends on the density of the mesh. Densities range from soft (hand pads and rolls) to hard (wheels and some discs). Use wet and dry. They are long lasting, nonrusting, nonconductive, and clog resistant.

Nylon mesh products are embedded with either aluminum oxide or silicon carbide abrasive grains. Aluminum oxide is more durable and more aggressive on hardened steel parts. Silicon carbide cuts faster and produces a finer finish on most materials."

I'm not saying that the green pads are bad, but they do have the potential to leave scratch marks.

I usually try some very fine steel wool with some WD40 to remove light rust on some of my carbon steel (1095 and 01) kitchen knives once in a while. I try to be good about washing and drying them after use.

Ric
 
I use no 7 rubbing compound to with a towel to remove rust then a soft cloth to remove the no 7. It really shines after. Surface rust is removed with use and unless u leave it rust for a long time your fine. After taking my stripped bk2 through a live sapling and letting it sit for a hour will show light rust spots, its just the way of the world and a little care fixes it right up
 
I have rescued an Old Hickory butcher knife from a truck bed. It's pretty pitted, I used vinegar and a green scrubby pad, then WD-40. It's no beauty queen, but it is still sharp and strong. The handle has some gaps from it's age, maybe the rust under the scales is more of a long term problem, that's why I dipped it in some Linseed oil. Heck, it was a free knife!
 
I'll take a rusty carbon blade anyday over a shiny stainless one.

The properties of good old fashioned high carbon steel far outweigh the fact that stainless doesn't rust so easily...JMO !
 
Okay, so rust is not that big of a deal, I guess I'm just worrying about something small too much. Thanks for the info everyone! Now I just have one more question. Is the light surface rust that will form on a non stainless blade a new layer that sits on top of the blade (kind of like a layer of oil sitting on th blade) or is it a thin layer that etches into the blade and replaces some of the steel and becomes part of the knife? And if it is a thin layer that etches into the blade, doesnt that mean you'll be taking off thin layers of your knife whenevr you remove the rust, gradually wearing it down so it kind of "shrinks"? Or is there a way to fix this/ remove rust without wearing down the blade a very thin amount each time? Sorry for the huge amount of questions, I just want to know everything about something before I buy it.
 
Adaam said:
Okay, so rust is not that big of a deal, I guess I'm just worrying about something small too much. Thanks for the info everyone! Now I just have one more question. Is the light surface rust that will form on a non stainless blade a new layer that sits on top of the blade (kind of like a layer of oil sitting on th blade) or is it a thin layer that etches into the blade and replaces some of the steel and becomes part of the knife? And if it is a thin layer that etches into the blade, doesnt that mean you'll be taking off thin layers of your knife whenevr you remove the rust, gradually wearing it down so it kind of "shrinks"? Or is there a way to fix this/ remove rust without wearing down the blade a very thin amount each time? Sorry for the huge amount of questions, I just want to know everything about something before I buy it.
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The red rust, by itself, actually removes some steel (that's the rusting process, as the steel is chemically altered into 'red' iron oxide). It will gradually eat down into the steel, IF it's left unattended. That's how the pitting happens. Removing some light rust at the surface, SOON after it begins to form, is much easier and won't result in much steel being removed otherwise. That's why it's important to stay on top of it.

Even so, it's not going to harm your knife, even if you do have to sand some steel away. That's all part of the life cycle of a knife that gets used. Don't worry about it.
 
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^ That.

I wouldn't worry about the tiny amount of steel that removing rust would remove, if you've ever tried to do any serious re-profiling on a hardened blade, you know what I mean. I worked over a fellow's Condor Bush Buddy here a while back, it had an extremely obtuse edge that needed to have the convex flattened out a bit to get the edge angle down. Just re-shaping the three-inch blade to knock twenty or so thousandths off the shoulders for about a half-inch up the blade took several minutes on a 50-grit belt. You're *not* going to remove any significant amount of the blade's mass by hand with a scotchbrite pad! :D
 
I once worked as a Blacksmith at a coal mine, all the tools we used were good old fashioned high carbon and many were 50 years old and older. Over the years they had rusted and been cleaned, used for years and then not used for years etc. These were hard use items, used and abused not polished and kept in a bedside drawer.
When I left the mine they were all still being used, they had not shrank to any point seen by the human eye and I am sure they are still being used by my friends that still work there !

Stop stressing and get some good old fashioned working mans steel !
 
Phydeaux said:
Never too sharp-

I would be careful using the green scotch brite pads. Some of them have silicon carbide abrasive in the matrix.

I noticed some scratches on a car window that I had scrubbed some bird stuff off. This is from the McMasterCarr Web site:

"Nylon mesh abrasives are used mainly as surface finishing products. They change the work surface without removing or damaging the base material. You can use them as an alternative to wire brushes, steel wool, sandblasting, buffs and compounds, rubber bonded abrasives, and sandpaper.

Also known as nonwoven abrasives, they are made of abrasive grain and nylon fibers. Flexibility depends on the density of the mesh. Densities range from soft (hand pads and rolls) to hard (wheels and some discs). Use wet and dry. They are long lasting, nonrusting, nonconductive, and clog resistant.

Nylon mesh products are embedded with either aluminum oxide or silicon carbide abrasive grains. Aluminum oxide is more durable and more aggressive on hardened steel parts. Silicon carbide cuts faster and produces a finer finish on most materials."

I'm not saying that the green pads are bad, but they do have the potential to leave scratch marks.

I usually try some very fine steel wool with some WD40 to remove light rust on some of my carbon steel (1095 and 01) kitchen knives once in a while. I try to be good about washing and drying them after use.

Ric
Click to expand...

Absolutely it will scratch the steel, it's very abrasive. I used the WD-40/scotchbrite example because almost everyone has those around. I usually don't use them, but I do have a chopper that I finished with a green scotchbrite specifically so I could clean it with the same. It's actually a nice finish, close to satin.
 
yes they are completely ruined. send them to me for proper disposal. :D :thumbup:





seriously they're fine. just clean it and be on your merry way.
 
Bill DeShivs said:
There are also a lot of good stainless steels.
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And therein lies a truism.

I own high quality knives of carbon steel, carbon tool steel, stainless steel and stainless tool steel. Any quality steel can be made into a quality blade, regardless of type.
 
When referring to steel, stainless should be 2 words - stain less. It will still rust (except for H1), and when stainless rusts, it's usually deep pitting rather than just surface corrosion.

If you don't mind the steel not being like a mirror, clean it REALLY good, then give it a forced patina. That's surface corrosion that looks grey, and actually protects it from further rusting. It will basically look like an older knife. Lots of us do that because we like the look anyway.

You can use vinegar, a potato, lemon, lime, etc. Stick your blade into it, and let it sit overnight. In the morning, you'll have a knife with more character, and it will be more resistant to rust!
 
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