natural patina vs. man-made

Now, I have a Case Pen knive in yellow CV, and although I STARTED the patina naturally, I did go and dip it in some lemon juice once just to speed things up. Should I remove the patina I applied and start over? Is that doable?
 
TheDoggyGuru said:
Now, I have a Case Pen knive in yellow CV, and although I STARTED the patina naturally, I did go and dip it in some lemon juice once just to speed things up. Should I remove the patina I applied and start over? Is that doable?
Click to expand...

The honest answer from me is: I don't know.

Although I am sure it would be OK to do that. I guess in that situation I would just clean the blades with simichrome or some other good metal cleaner and just continue using it for EDC.. :)
 
If it was me I think I'd leave it alone as long as there isn't any problem, like rusting. I'd just continue useing it as is. As long as you use it your continueing the process and adding layers I think. And, I now agree with Sunnyd that is the best way to get a patina. Heck if you really liked drinking Tom Collins you'd be cutting up lemonds every day instead of apples. :)
 
Some one mentioned in another thread about strawberies. We had a strawbery desert after dinner saturday night. WOW! They left the clip blade on my Case Trapper a nice dull gray.

I tend to agree that the natural patina is better. I was chopping wood one day and found an old Old Hickory boning knife laying in the dirt. It did have a little rust around the handle area, but the remainder of the blade was brown from (assuming) years or use and was free from rust. I gave the blade a few swipes with a wire brush and cleaned the handles up a bit. Now it is proudly serving again.
 
Wildcat i noticed the same while making jelly with Strawberries and Rhubarb over the weekend. It produced a patina faster than most apples do. I was using a relatively new Dexter Russell sheep skinner, and after the cutting was done the blade had started a decent patina, it was a nice added bonus. Sunnyd, I am from New Hampshire every season holds different adventures and new layers of patina for the old EDC, no matter what blade it is. Joe
 
From 06/25/2007-07/04/2007 my schrade 96 OT was in my pocket nonstop while on Georges Bank. Ten days of NO maintenance except for touchups, and I used it to cut everything, from sharpening pencils, to putting butter on bread, to cutting apples, pears, and oranges for dessert (It was a portuguese boat, and there was a lot of fruit). I handled and used this knife when my hands were wet with seawater, covered in fish slime, and in other extreme conditions. Oftentimes it went right back into my pocket and was forgotten about, and I think it only got a fresh water rinse when I was going to use it to cut food. It was never oiled during the trip. Actually, I replaced it with my dodo for a while, and since the 20th of July it has sat around, uncleaned since I got in from offshore.

It's condition? It is a little tighter to open, and there is less snap than new. There is some rust on the spey blade, where the patina wasn't as complete as on the clip blade. I have not tried to remove it with abraisives yet. Just this morning I put some WD-40 on the blade to try and break the rust up. I'll give the knife a full overhaul when I get a free minute to go buy some supplies.

All in all, I'm pretty impressed with this knife, and with carbon steel in general. To put it in perspective, I did not take care of my issued knife (a Dexter Russell Hi-Carbon 1376 boning knife) either on this trip, and it had no patina on it, and rusted up quite badly.

This in itself tells me that a patina is a natural protectant to a carbon steel blade as the Dexter was used to actually cut fish, was rinsed with seawater, and put back in its sheath. The Schrade was usually stuck in my pocket after use and not rinsed until I needed it to cut food. The schrade was used exponentially more on this trip than the dexter, but they both suffered an equal amount of neglect.

when I get to clean this Schrade up again, it will probably find its way back into my pocket.

Pete
 
I think a natural patina works fine. Here's my old Hen & Rooster from the mid '70's....sliced a few hundred apples over the years. Never made an effort to control it in any way.

DSC_0002-5.jpg


It's merely controlled rust, almost like rust bluing on a firearm.

Best, JB
 
OK everybody, I'm sorry I earlier poo-pooed the whole idea of patinas providing rust protection, no matter how they are induced. I'm wrong once in awhile, maybe every year or two on average. :D I do hope this smooths a few ruffled feathers.

I still think that occasional thin applications of the oil or wax of your choice will provide somewhat more protection against rust and corrosion, though the best situation might be a combination of both patina and a rust preventative, the reason being that I believe patina is the result of slight acid etching of the surface of carbon steels. Acid etching not only has a "conversion" effect on the surface molecules of the steel, but the microscopically roughened surface will then hold any protectant you apply longer. The term "conversion" in this case refers to the process of converting the surface molecules to something other than what they originally were. For example, simple rust is the conversion of those iron atoms and/or molecules in the steel to a form of iron oxide. Salt water corrosion is a little different, however.

It's much the same principle used on the older US military small arms (and on the remaining steel parts of the newer ones) that were and are "parkerized." The parkerized finish certainly holds oil, grease, and synthetic protectants better and longer in use. Fairly obviously, somebody named Parker must have developed the process long ago. There were at least two basic types or formulas of parkerizing, too. The earlier one produced more of a gray-green finish, especially in conjunction with arsenal storage using Cosmoline, which is a thick, sticky, but very effective preservative grease in use for many decades by the military for long term storage. The later type of parkerizing produces a gray-black or simply a black finish, and it probably works even better for rust protection.

At the moment I don't remember the details of the differences in the two basic parkerizing formulas, but I doubt very many folks care anyway. I remember the details being published in an article by the NRA several years back, and I'm sure they can now be found online in minutes. I think the earlier version of parkerizing used phosphoric acid as the main ingredient, and sometime I may check into using some of that to produce a "serious patina" on knife blades. I know you can buy relatively small (quart?) quantities from the usual gunsmithing suppliers like Brownell's and Midway.

In case anybody else wants to try it, phosphoric acid is used in diluted form in some institutional bathroom cleaners, or it was fairly recently, and I think it's available in a stronger form in some products sold in auto parts stores for rust conversion prior to painting. I think Rust Kill is one brand I've seen.

Whatever it is (an acid?) that the bladesmiths use to bring out the pattern in Damascus blades might be worth investigating with respect to patinas, too.

But for use in and around a salt water environment, I still think one of the "stainless" steels is the most practical choice by far. That's why stainless steels were developed. I'd bet money the old time sailors would have killed to own good stainless steel knives like those we can choose from today.
 
Pete great report. I have a Opinel that I gave the lemon juice dunk patina and that also seems to protect against the red rust beast. It is a very dark black patina on it and as I haven't given it as harsh of a test as yours it hasn't had a spec of rust. As Sunnyd said the more layers you can get on, darker the patina, I think the more it protects.
 
OK everybody, I'm sorry I earlier poo-pooed the whole idea of patinas providing rust protection, no matter how they are induced. I'm wrong once in awhile, maybe every year or two on average. :D I do hope this smooths a few ruffled feathers.

I still think that occasional thin applications of the oil or wax of your choice will provide somewhat more protection against rust and corrosion, though the best situation might be a combination of both patina and a rust preventative, the reason being that I believe patina is the result of slight acid etching of the surface of carbon steels. Acid etching not only has a conversion effect on the surface molecules of the steel, but the microscopically roughened surface will then hold any protectant you apply longer. The term "conversion" in this case refers to the process of chemically converting the surface molecules to something other than what they originally were. For example, simple rust is oxidation, the conversion of those iron atoms and/or molecules in the steel to a form of iron oxide. Salt water corrosion is a little different, however, because of the sodium etc. dissolved in sea water.

It's much the same principle used to produce a protective coating on the older US military small arms (and on the remaining steel parts of the newer ones) that were and are "parkerized." The parkerized finish certainly holds oil, grease, and synthetic protectants better and longer in use. Fairly obviously, somebody named Parker must have developed the process long ago. There were at least two basic types or formulas of parkerizing, too. The earlier one produced more of a gray-green finish, especially in conjunction with arsenal storage using Cosmoline, which is a thick, sticky, but very effective preservative grease in use for many decades by various militaries for long term storage. The later type of parkerizing produces a gray-black or simply a black finish, and it probably works even better for rust protection.

At the moment I don't remember the details of the differences between the two basic parkerizing formulas, but I doubt very many folks care anyway. I remember the details were published in an article by the NRA several years back, and I'm sure they can now be found online in minutes. I think the earlier version of parkerizing used phosphoric acid as the main ingredient, and sometime I may check into using some of that to produce a "serious patina" on knife blades. I know you can buy relatively small (quart?) quantities from the usual gunsmithing suppliers like Brownell's and Midway.

In case anybody else wants to try it, phosphoric acid is used in diluted form in some institutional bathroom cleaners, or it was fairly recently, and I think it's available in a more concentrated form in products sold in auto parts stores for rust conversion prior to painting. I think Rust Kill is one brand I've seen, though that turns rust from red to black, so maybe it's not phosphoric acid it that product after all. Read the ingredients or the Material Safety Data Sheet (MSDS), a document the manufacturer or distributor is required by law to furnish anyone who plans to buy or use it. MSDSs are required by the federal government (OSHA I think) to be kept on file in a binder and available for reading at all times by the designated safety officer of any agency or organization that uses almost any commercial product.

Whatever it is (an acid?) that the some bladesmiths use to bring out the pattern in Damascus blades might be worth investigating with respect to patinas, too.

But for use in and around a salt water environment, I still think one of the "stainless" steels is the most practical choice by far. That's why stainless steels were developed. I'd bet money the old time sailors would have killed to own good stainless steel knives like those we can choose from today.
 
OK everybody, I'm sorry I earlier poo-pooed the whole idea of patinas providing rust protection, no matter how they are induced. I'm wrong once in awhile, maybe every year or two on average. :D I do hope this smooths a few ruffled feathers.

I still think that occasional thin applications of the oil or wax of your choice will provide somewhat more protection against rust and corrosion, though the best situation might be a combination of both patina and a rust preventative, the reason being that I believe patina is the result of slight acid etching of the surface of carbon steels. Acid etching not only has a conversion effect on the surface molecules of the steel, but the microscopically roughened surface will then hold any protectant you apply longer. The term "conversion" in this case refers to the process of chemically converting the surface molecules to something other than what they originally were. For example, simple rust is oxidation, the conversion of those iron atoms and/or molecules in the steel to a form of iron oxide. Salt water corrosion is a little different, however, because of the sodium etc. dissolved in sea water.

It's much the same principle used to produce a protective coating on the older US military small arms (and on the remaining steel parts of the newer ones) that were and are "parkerized." The parkerized finish certainly holds oil, grease, and synthetic protectants better and longer in use. Fairly obviously, somebody named Parker must have developed the process long ago. There were at least two basic types or formulas of parkerizing, too. The earlier one produced more of a gray-green finish, especially in conjunction with arsenal storage using Cosmoline, which is a thick, sticky, but very effective preservative grease in use for many decades by various militaries for long term storage. The later type of parkerizing produces a gray-black or simply a black finish, and it probably works even better for rust protection.

At the moment I don't remember all the details of the differences between the two basic parkerizing formulas, but I doubt very many folks care anyway. I remember the details were published in an article by the NRA several years back, and I'm sure they can now be found online in minutes. I think the earlier version of parkerizing used phosphoric acid as the main ingredient, and sometime I may check into using some of that to produce a "serious patina" on knife blades. I know you can buy relatively small (quart?) quantities of parkerizing solution from the usual gunsmithing suppliers like Brownell's and Midway.

In case anybody else wants to try it, phosphoric acid is used in diluted form in some institutional bathroom cleaners, or it was fairly recently, and I think it's available in a more concentrated form in products sold in auto parts stores for rust conversion prior to painting. I think Rust Kill is one brand I've seen, though that turns rust from red to black, so maybe it's not phosphoric acid it that product after all. Read the ingredients or the Material Safety Data Sheet (MSDS), a document the manufacturer or distributor is required by law to furnish anyone who plans to buy or use it. MSDSs are required by the federal government (OSHA I think) to be kept on file in a binder and available for reading at all times by the designated safety officer of any agency or organization that uses almost any commercial product.

Whatever it is (an acid?) that the some bladesmiths use to bring out the pattern in Damascus blades might be worth investigating with respect to patinas, too.

But for use in and around a salt water environment, I still think one of the "stainless" steels is the most practical choice by far. That's why stainless steels were developed. I'd bet money the old time sailors would have killed to own good stainless steel knives like those we can choose from today.
 
Would the moderator please delete my triple (?) post on this page? Thanks. I tried to do that, but obviously without success. Sorry about that!
 
Hi! I have learnt a lot about carbon steel knives through the posts above. I have an Opinel No. 7 and a german knife stamped Frider. Herder Made In Solingen Germany. This knife has a 7 inch forged sheepsfoot blade with a rat-tail tang that goes in a roundish wooden handle with a steel ring that tightens the part where the blade enters the handle. This knife is seen in certain fruit shops around Singapore and cost about SGD$60. The knives at the fruit shops are usually have a very dark grey, almost black patina.
When I got the knife, I could tell that a considerable amount of manual work made it as the blade wasn't exactly flat. So, I got the sharpening stone out and rubbed the whole blade over it to make it flat and convex it a little at the edge. Very sharp, despite the rough finish.
I understand that a rough finish is more susceptible to rusting and yes, the knife has little spots of rust all round but also a light grey patina.
My question is how do I sharpen the knife in a convex manner while keeping the patina?
Thanks
 
"Natural Patina" would make a nice name for a Latin jazz or blues band :cool:
 
Seems there is some misinformation here....good stuff too, of course. Let's not get the good lost amongst the bad, though.


We're talking about 3 different things here:

1 - patina
2 - rust
3 - pitting

You can, of course, get all of the above in just one fit of casual neglect (just happened to me too!)

But they are 3 different things/processes/results.

Patina is a reaction of the surface of the steel with a chemical. No matter how many "decades" or "minutes" it took you to get it on there...it is superficial...only on the surface...and very, very thin/shallow. The important part is that you have not lost any material.

Rust is an extreme oxidation reaction that also happens on the surface...producing a new material - iron oxide. There are also 2 kinds of rust, surface rust (bright orange) and deep rust (red/black). The first is simple to remove and results in only minimal damage to the steel. The second is more difficult to remove (requireing buffing/etc).

Pitting is the breaking down of the steel from severe neglect. You can certainly get pitting with no rust. Leave a carbon steel blade in FeCl too long and it will get pitted.


A lot of old knives have various combinations of the above which gives them character...something that can't easily be duplicated.

BUT....and this is a BIG BUTT.....the processes are the same, whether they take seconds or years. "Man-made"..."forced"...techniques can very easily reproduce the effects of time/weathering/corrosion.

It is simply a matter of the steel reacting to a chemical or air, etc.

But like I said...the "forced" patina will not have the same "character" as a patina that formed over time...whose owner watched it build over the years...or maybe you found grandpa's ole whittler...the "character" makes the patina special.




Now, for the OP's question:


No carbon steel knife should be used in saltwater applications. There are no proven rust-preventative techniques strong enough to overcome the effects of saltwater...even on most stainless knives. You should, in those circumstances, be extremely vigilant with your maintenance if you want to avoid rust. Even simple exposure to the air will do it.


I learned the hard way that just boiling some chlorox in the shop was a great way to rust every piece of carbon steel in there.


If you want a finish for a carbon steel knife that is going to be able to rust and not look back....then you'll need more aggressive patina techniques (like boiling it in chlorox...or leaving it a jar of vinegar for a few days...)

Here's an example of the chlorox treatment:

attachment.php


This knife will, indeed, rust. It kept rusting on its own for days after I cleaned and buffed it. But I guarantee it won't look "worse" from any further rusting/pitting! :D
 
Daniel Koster said:
If you want a finishd
Here's an example of the chlorox treatment:

attachment.php


This knife will, indeed, rust. It kept rusting on its own for days after I cleaned and buffed it. But I guarantee it won't look "worse" from any further rusting/pitting! :D
Click to expand...

That knife couldn't look any worse! :barf: LOL Sorry, man. Couldn't resist! :p
 
db said:
I'm confused, I thought patina was the black oxide form of rust.
Click to expand...

Black oxide is a form of patina.

A patina can be almost anything that shows age/wear/use/exposure to elements/etc.
 
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