The Patina on carbon steel Opinel knives is a common thing to happen. Here is how to prevent them, or force them!
A Patina on carbon steel knives is a form of corrosion that tends to happen when handling the knife in wet or humid conditions. With Opinel knives that tend to happen from being in a sweaty pocket. Or cutting something with acids or tannins in it. For example, cutting a hazel branch tends to discolor Carbon Steel Opinel knives quite a bit.
Quick Jump Guide
It can bother some people to have their knife no longer in pristine condition. However, keep in mind that Opinel knives are workhorses and very affordable. If it bothers you a great deal I would recommend getting the INOX or stainless steel version of the Opinel knives.
Preventing a Patina on Opinel knives
Preventing the forming of a patina on Opinel knives is a constant task. It requires paying attention to wiping the blade of the Opinel knife after each and every use. And to make sure it is dry after each use. You can do this with a cloth or on your clothing.
Once every while it will be necessary to oil the knife with some food-grade oil. Since Opinel knives are used for food prep a lot it is better to use food-grade oil like Olive Oil or Sunflower Oil.
If you do not plan to use an Opinel knife for a longer time than it also a good idea to not store the knife in a shed, humidity can discolor the blade already. So store it in a dry and warm place inside the house. Or wrap it in an oil cloth to prevent the moisture from penetrating and causing rust.
This will prevent the patina from forming on the Carbon steel Opinel knives. It still can happen of course in a blink of an eye, to get rid of the patina you can use a dish scrubber and some scrubbing compound. Used for cleaning silver and bronze.
Forcing a Patina on Opinel knives
When you however want to force a patina on Opinel knives you can do this a number of different ways. Having a Patina on Opinel knives is not necessarily a bad thing. Having the right amount doesn’t only look cool and used, kinda like Boba Fett’s armor. But it also forms a protective layer to prevent further rust from developing as quickly.
That is why it is also often forced on the knives. You can do this in a bunch of ways. Easiest is to just prepare yourself a nice lunch board with your Opinel knife. Cut yourself some Spanish Fuet or Chorizo sausage, some cheese, and scoop some mustard on a ham sandwich. And don’t clean it as thoroughly as usual.
With daily use, a natural patina will form on pretty much any carbon steel knife. If however, you want to use common household products you can do this with the following products.
Ordinary yellow mustard can be used on the blade to create a nice pattern patina on your Opinel knife. Smear it on in a pattern or cover it completely. Wait until the following morning and wipe it off before cleaning.
Using an acid like White Vinegar is food safe and in my experience gives the cleanest result for a patina. You can soak a paper kitchen towel in White Vinegar and wrap it around the blade overnight.
This will form the Patina in an even way around the blade and will give way less mess than with the Mustard way. You can also submerge it in White Vinegar for an hour or two. I wouldn’t recommend that method overnight though.
Conclusion on Patina’s
Having a Patina on an Opinel knife is not necessarily a bad thing. However, you still have to maintain the knife. Having a patina on it does not prevent rust from forming in saltwater environments for example. Therefore if you want to prevent it all together go for an Inox or Stainless steel Opinel knife.
For further reading on Opinel knives, I recommend my article on the Opinel Inox vs Carbon steel. That article further explores the pros and cons of both steel types. And if you want to get your very own Opinel knives you can do so via the following links, these are affiliate links where I get a kickback for the purchase. At no added costs to you.