Help me understand patinas please. CV Case knife on the way

[bladeboss]

I called this guy to get some answers ....

He just shook his head and went back to workin.'

-- Mark

This alone told me more than the whole thread.
And it was funny.

 

[Finedges]

I've had this GEC with a 1095 carbon blade for only a week or so. When I got it, I cleaned the blade with an alcohol wipe, and peeled an apple for my daughter. As soon as I finished, wiped it clean. Today at work, peeled an apple and sliced an orange for myself with it. Wiped it down right after. The GEC 1095 takes some beautiful coloring from what I've seen. I have never just stuck a knife in anything to speed a patina along. I've just had them come from use. Anyway, just enjoy the knife and use it, and it will come along nicely.

 

[Obsessed with Edges]

This is my Schrade USA 8OT (1095 steel). The patina on the clip blade is all from slicing grapes, pickles, and then more grapes, over some weeks' time. The grapes by themselves left a somewhat lighter, subtler patina. Then, when I was fiddling around with the pickles, I had dipped a piece of paper towel into the pickle jar (after I'd finished off the pickles), and wrapped it around the blade. Left it in place for probably a couple hours. That actually left some red rust on the blade , so I cleaned that up by scrubbing with baking soda, then thoroughly rinsing under running water, and pouring isopropyl alcohol over the blade to thoroughly dry it. Initially, I wasn't too fond of the pattern left by all this. But, I just happened to have some more grapes handy, so I sliced a few more of those, and let the juice coat the blade. Let that sit for maybe 30 minutes, then cleaned it up. That really darkened and evened up the patina, and it's been getting even darker after a few days' time. I touched up my edge on some sandpaper and then stropped it with both diamond compound and then on green compound. The edge has been very nicely highlighted in the process. Overall, the look of it has grown on me. I'll be having some more grapes this evening, might try a tomato also. So, onward it goes...

 

[bladeboss]

She's here!

 

[jackknife]

She's here!

She's a purty one. Take care of her, and she'll serve you for many years to come. :thumbup:

 

[Thalestin]

She's here!

What a cute little knife. Enjoy her in good health

 

[bladeboss]

Thank you!

 

[Sesp77339]

Here is my knife with a natural aged patina

 

[ElKabong]

Here's a CV Sodbuster I found in a pawn shop
It was pretty crusty, I cleaned it up a little with 0000 steel wool and oil
The patina on it looked pretty nice and there were no pits , so I left it alone
Looks as good to me as any artificial patinas I've seen

 

[agile_1]

Super great semi technical discussion of the formation of the Fe2O3 (red) vs Fe3O4 (gray/black) oxides of iron. Hope it is ok to link to the forum here...
Rust (red) vs Patina (black)

Scroll down to the end of the first page for the mother lode. But the whole thread is worth reading.

 

[knarfeng]

Rather than "hope", next time ask first. You can PM Gary and me.
It is preferred that posts not have a sole purpose of linking to another forum.

edited to add:
Aside from that, while I do not disagree with the chemistry, I do disagree with their purported result. (And I say that as one who has a degree in chemistry and is the author of the corrosion prevention document of the aerospace company for which I work.)

Black oxide does not form an adhering impermeable barrier. It forms a porous barrier, which is of limited use in preventing red rust unless oiled.

 

[agile_1]

Rather than "hope", next time ask first. You can PM Gary and me.
It is preferred that posts not have a sole purpose of linking to another forum.

edited to add:
Aside from that, while I do not disagree with the chemistry, I do disagree with their purported result. (And I say that as one who has a degree in chemistry and is the author of the corrosion prevention document of the aerospace company for which I work.)

Black oxide does not form an adhering impermeable barrier. It forms a porous barrier, which is of limited use in preventing red rust unless oiled.

Ok knarfeng - thanks for the heads up regarding PM's.

So is the general consensus that the bulk of a knife patina is Fe3O4? If so - without considering steel composition and agents (food etc.) that the steel has been exposed to, it is certainly reasonable to expect that patinas are a mix of Fe compounds in various concentrations.

In any case I have a couple of well patinated carbon steel folding Opinels in my kitchen that I use for food prep. I do not oil them with anything aside from the fats from food, butter, cooking oils and oil from incidental skin contact. That seems to be more than enough oil to prevent excess red rust. There are some areas in the patinas that are darker than others and there are also some spots. But they are all "natural" patinas from exposure to a variety of foods and common kitchen use.

So - as far as the OP's mention of cultivating even patinas, techniques exist to do that. You would have to carefully control the environment (kind of like the "knife in the potato technique" ) until you got the look you were after and then maintain it over the long term. Kind of a pain if you ask me. If it is a user knife the evenness of the patina might be downright impossible to control. Most of the knives pictured in this thread (and all my kitchen Opinels) show various degrees of spotting and evenness.

A couple pics. Not so great but you can see the difference between the SS #08 and the carbon steel #06 and #10.

Also compare the Opinels to a non-patinated Case CV Trapper. The Trapper is now a safe queen. Very lightly used and carried a few times (a dozen or so?) when new. Now it sits in its box. If I lived in a high humidity location like the south eastern US it would probably be rusting away by now.

 

[leghog]

I have no problems with a forced patina on a knife any more than I do bluing on rifles. They both serve the same purpose --- controlled oxidation.

 

[jon_slider]

If I read knarfeng right the following statements are all true:

1. Patina does not protect unless it is oiled.
2. Patina is porous, so it acts like a sponge that holds oil.
3. Unoiled patina does not protect.
4. Wiping a patina with alcohol removes the protective oil.
5. Wiping a patina with oil protects the blade from rust.

So all the people who force patinas to protect their blades, are only gaining protection IF they also oil the patina. Same with gun bluing.

did I get that right?

 

[leghog]

So all the people who force patinas to protect their blades, are only gaining protection IF they also oil the patina. Same with gun bluing.

With a patina or hot blue you need not oil nearly as often provided you don't enter salts (think fingerprints here) into the equation.

 

[b2edhmep]

To oil or not to oil. If you live in the deep south like I do you should lightly oil it occasionally. The humidity alone will rust a knife. Sweat will destroy a carbon blade. Carbon blades have been around for centuries, a little maintenance and they will last a life time. A patina will form a protective covering or stain on a carbon blade. It is similar to the natural browning of a gun barrel. The Brown Bess musket used by the British army for almost two centuries was issued with a barrel in the white, no stain. The gun developed a light cote of rust with use. The rust was rubbed off and barrel lightly oiled. Over a period of time the barrel developed brown stain. This stain, like a patina, protected the barrel from further rust if cleaned an oiled regularly.

 

[sunandsteel]

I've had this GEC with a 1095 carbon blade for only a week or so. When I got it, I cleaned the blade with an alcohol wipe, and peeled an apple for my daughter. As soon as I finished, wiped it clean. Today at work, peeled an apple and sliced an orange for myself with it. Wiped it down right after. The GEC 1095 takes some beautiful coloring from what I've seen. I have never just stuck a knife in anything to speed a patina along. I've just had them come from use. Anyway, just enjoy the knife and use it, and it will come along nicely.

I agree. By the way what knife is that?

 

[jc57]

If I read knarfeng right the following statements are all true:

1. Patina does not protect unless it is oiled.
2. Patina is porous, so it acts like a sponge that holds oil.
3. Unoiled patina does not protect.
4. Wiping a patina with alcohol removes the protective oil.
5. Wiping a patina with oil protects the blade from rust.

So all the people who force patinas to protect their blades, are only gaining protection IF they also oil the patina. Same with gun bluing.

did I get that right?

That is also my understanding.

 

[knarfeng]

An added complexity is that the conditions under which black oxide forms are not conducive to the formation of red oxide. So if you keep your blade dry, it may not form red rust, even if you don't oil it.

I have an old carbon steel electrician's knife, which I used when I did electrical work as a young man in the mid 70's. It was given to me in used condition by my boss, so it likely dates from the 60's. Never oiled. Never overly protected as it rode in an electrician's pouch. The blades got used and exposed to dampness, but were wiped dry. The screwdriver blade was never used. Note that the screwdriver blade is still bright and shiny, even without having been oiled. No patina. No black rust. No red rust. So it all just depends.



The alcohol part also has many variables. Depends on what you use for "alcohol" and how much you use. Alcohol is very polar. Oil is non-polar. Polar and non-polar don't mix as in "oil and water". So for example, if you used 70% rubbing alcohol and gave the knife a quick rub, the oil might remain. But if you used a lot of alcohol, or if you used 99% rubbing alcohol, the oil might well be removed.

 

[agile_1]

An added complexity is that the conditions under which black oxide forms are not conducive to the formation of red oxide. So if you keep your blade dry, it may not form red rust, even if you don't oil it.

I have an old carbon steel electrician's knife, which I used when I did electrical work as a young man in the mid 70's. It was given to me in used condition by my boss, so it likely dates from the 60's. Never oiled. Never overly protected as it rode in an electrician's pouch. The blades got used and exposed to dampness, but were wiped dry. The screwdriver blade was never used. Note that the screwdriver blade is still bright and shiny, even without having been oiled. No patina. No black rust. No red rust. So it all just depends.

The alcohol part also has many variables. Depends on what you use for "alcohol" and how much you use. Alcohol is very polar. Oil is non-polar. Polar and non-polar don't mix as in "oil and water". So for example, if you used 70% rubbing alcohol and gave the knife a quick rub, the oil might remain. But if you used a lot of alcohol, or if you used 99% rubbing alcohol, the oil might well be removed.

I would add that alcohol (70% isopropyl) contains water. The ingredients in drugstore grade alcohol are 70% isopropyl with an inactive ingredient of water - assuming approx 30% water in a freshly opened bottle. Not sure about alcohol wipes. I clean my kitchen Opinels with soap and water and dry well. No red rust but then again they see cooking oils and fats on a daily basis.