Best forced patina for chefs knives

T

Tyler.t76

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May 19, 2022
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Ok guys I need some help with something. I have a few chefs knives I’m working on that will be sent out to people and I don’t want them to have to deal with the shock of patina on a carbon steel knife, the situation is complicated so I can’t explain fully here. I’m looking for an even dark finish, I’m thinking etch in ferric and then in coffee. I’m wondering if I should skip the ferric and just do the coffee, if this process will give decent resistance to any shocking discoloration, as well as tips to improve the durability so it does not wear away the first time they use it and start leaving colors on their food. The steel is 80crv2 if that helps. I will obviously be giving a care sheet with the knife that explains the ins and outs of carbon steel knife care to minimize the worried emails that their knife is turning their tomatoes black and things of that nature.

In short, tips on getting a good protective layer on 80crv2 chefs knives, something durable that won’t wear super fast and that will not patina as noticeably. And definitely the best ways to make sure it’s not leaving colors on the food cut with it.
 
I have done that exact method you mentioned with good results as an initial finish but patinas are not permanent (very shallow surface penetration) and will continue to discolor (and even wipe away) with use in the kitchen…

Sorry for the crappy photo but both these knives started with the finish as mentioned above (ferric and coffee) - seen by the heel on the bottom knife:FADE7CF3-2B7D-4E29-9606-6DCE99C1F89B.jpeg
 
ISKski said:
I have done that exact method you mentioned with good results as an initial finish but patinas are not permanent (very shallow surface penetration) and will continue to discolor (and even wipe away) with use in the kitchen…

Sorry for the crappy photo but both these knives started with the finish as mentioned above (ferric and coffee) - seen by the heel on the bottom knife:View attachment 1977885
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Thanks! I will continue my search for answers
 
Rust bluing is the most durable ive done so far...... but me personally.

I don't want "someone else's" patina on MY knife.... haha.

I agree with giving them care instructions, and inform them of what is naturally going to occur.
Let them make the memories, don't take away their fun!
 
Crag the Brewer said:
Rust bluing is the most durable ive done so far...... but me personally.

I don't want "someone else's" patina on MY knife.... haha.

I agree with giving them care instructions, and inform them of what is naturally going to occur.
Let them make the memories, don't take away their fun!
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I fully agree with you, I won’t be in direct contact with these specific people but perhaps I will leave detailed explanations on a note as well as contact info to clear up anything.
 
The best approach is to educate the client on simple carbon steel and how they form a natural patina. They absolutely cannot treat it like a stainless blade and shouldn't be led to believe so. If you fear patina will be a shock, this may not end well.
 
Rick Marchand said:
The best approach is to educate the client on simple carbon steel and how they form a natural patina. They absolutely cannot treat it like a stainless blade and shouldn't be led to believe so. If you fear patina will be a shock, this may not end well.
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I agree, I’m happy to educate them, but you know how some people are haha. I think I’ve decided I’ll leave them without a patina, if they decide to ignore what I say, or are paranoid about it they can always send it back and I can give it to someone who will respect it more
 
i have found it to be a good practice to force a patina to give someone a foundation to build their own. In my experience there has only been a few customers who requested no patina.

I have found a pretty durable method similar to how damascus is etched. Lots of pretty short etches followed with a light scrub under water. It helps to rinse with hot water and use a blow dryer to dry off the blades.

Here I have used the method above with mustard/vinegar as a base..the condiment you use is only important in terms of the texture in creating a pattern ... well, and the strength of the vinegar.

 
Boiling the blade in a TSP and water mix after forcing a patina with FC will help make it more permanent.
 
I have a Masahiro carbon gyuto. I echo Crag the Brewer Crag the Brewer on this. Tell them how to build their own natural patina. Forcing it seems to build too much loose surface oxide. Cut food, clean it religiously, dry it immediately, done. Nice stable patina that doesn't come off every time you cut something. A rust eraser is a good suggestion too if they find they need to start over, super cheap.
 
Thanks everyone! I’ve decided to just leave them without a patina, and provide a detailed explanation of what will occur. Does anyone have a good source for a write up for that, something detailed but not overly lengthy?
 
Here is a good write up I just made- Clean and dry immediately after use. As you use this knife, it will change colors based on the food you cut, this is a feature not a flaw. Clean and dry immediately after use. If you do not like your knife to patina, purchase one with stainless steel.
 
Here's what I sent out with a utility and paring knife set I gave as a wedding present earlier this year.

These Blades are made of 80CRV2 steel (Swedish Saw Blade Steel). It has been forged, ground, quench hardened and tempered, all by hand. With this you will see the benefits of better edge retention, faster sharpening, and quicker honing for interim maintenance over commercially prepared stainless steel knives. These benefits though do come with a sacrifice. Being carbon steel these blades are susceptible to rust and discoloration. Rust will form in a matter of minutes if the knife is left wet or soaking in the sink. This is not to be confused with a patina that will develop over time when the blade comes in contact with acidic food. Remember, rust is red, where patina can be just about any colour but red. With the proper care these blades will eventually turn dark brown/grey/black if you build a strong patina.

A patina is very similar to the seasoning in a cast iron pan, you slowly build up a strong, resilient seasoning and your pan is non stick, and if you build a strong, dark patina on a carbon knife it will be more resilient to rusting from coming in contact with water. It's not that this is a lot of extra work, and this is really all the extra maintenance that a carbon knife requires, but it requires building the habit of wiping it down quickly, every single time.

The handles have been constructed using a stabilized hardwood and have been finished with an all natural bees wax seasoning. Over time, this finish may dull, but can be restored simply by hand rubbing bees wax back into the handle, and wiping clean. Please do not soak this in water, or use harsh chemical cleaners as it can damage the finish.

I hope you truly enjoy these knives and use them often to build a patina like a story. They are one of a kind and were built solely for you.


Feel free to use.
 
There was a Knife Steel Nerds article a while ago about some research on how water drying on stainless will damage the edge even if it doesn't leave a lot of corrosion. My conclusion is that proper care for a stainless knife is the same as for a carbon steel knife, so that's what I tell customers. The care is the same, carbon steel will just punish you more for not doing it.
I don't force a patina generally, but i do this as a side gig so I'm in the position of being able to be a bit quirky :P

Stacy E. Apelt - Bladesmith said:
Boiling the blade in a TSP and water mix
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What do you mean by TSP? I assume this is the same chemistry as boiling after rust bluing, so this makes sense.
 
TSP will completely neutralize any Ferric Chloride and also do something chemically that makes the surface oxide more resistant to rubbing off. I could take a blade out of teh FC and wash it in running water while rubbing with a paper towel and most of the dark color would rub off. Boiling in TSP (one cup TSP to a gallon of water) seems to stabilize te dark. I don't do any more than a quick rinse and into the boiling pot. The pot I use is a tall thin stock pot called a bain marie. Any 12 quart stock pot will work. Boil for a good 30 minutes and then take out of the pot. Wipe off and hang in the air to air dry.

Boiling in TSP is a very wise thing after etching damascus, as there is often FC or acids trapped in invisible cracks, flaws, and incomplete welds. This will show up as rust or corrosion in the future, but the TSP stops that completely.
 
Ah, i see! So it's probably converting the Fe3O4 formed by the Ferric Chloride into Iron Phosphate, which is presumably more tightly bonded to the underlying steel.
It's very basic, from a safety perspective there are other things i would use to neutralise the FeCl, but you want the phosphate to form that coating so necessary for that. Disodium Phosphate may be another option, lower ph?
Thank you, that's all interesting to know

damn, reading about pKa and stuff takes me back
 
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