Forcing a Patina on Bushcraft Knives

Wednesday, 08 September 2010 18:32

Ashley-Cawley

Posted by Ashley Cawley

What is 'patina'?

When talking about metal, patina is a fine layer of surface rust (or staining) that naturally builds up as a result of oxidation. This form of staining or surface-rust is not the same as the very corrosive red-rust that can damage a blade.

A good patina on a blade can actually form a protective barrier on metal, stopping further oxidation & corrosive rust from setting in, this can be a plus side to having a patina your blade. Some people also find a good patina on a knife-blade aesthetically pleasing, it's a matter of taste; some might like the shiny new look of a blade whilst others might prefer the old, used look of a trusty tool.

Oxidation and patinas obviously have more of an effect on high carbon steel blades more than say stainless steel.

So what is 'forcing patina'?

Patinas will occur naturally on a blade through normal use, especially when using a knife for common Bushcraft tasks; cutting through bark, wood, plants etc. you will often notice that natural chemicals react with your carbon blade. It can take a long time to form a good patina depending on how often you use your blade. Forcing a patina on a knife blade is to speed up the process artificially using chemicals, which allows you to create the equivalent of 15-20 years worth of natural patina in just 1 hour!

Forcing a patina can even be done using naturally occurring citric chemicals; for example apples and even potatoes can be used. Some people prefer to use mustards with a high vinegar content. A common and easy method for creating a patina is to use vinegar and this is the method I gave a go...

The equipment I used was simple and is shown on the right:

Carbon Steel Knife
Malt Vinegar
Rag or Towel

On my first attempt I would simply soak the rag in vinegar and then wrap it around the blade of my knife, leaving it for one hour.

Here is my blade before I started:

When using this method with the vinegar soaked rag you will get an uneven pattern as not all areas of the rag & vinegar will make contact with the blade. I was quite happy with the results:

And here is the same process on my Opinel No.8 Knife

Before

opinel-before

And after 1 hour soaking in wet vinegar rag

opinel-after

opinel-after2

opinel-after3

As you can see in the last image (above) the patina wasn't even on one side of the blade, this is just due to how vinegar soaked rag made contact with different areas of the blade. I simply repeated the process on the Opinel for a further 40mins and it evened out the patina nicely.

If you fancy giving this a go, please get in touch by leaving a comment below and let me know what you used and how it turned out.

Further Resources on Forcing-Patinas:
A good set of videos by Cutlerylover...

Comments (10)

Hey Ashley brilliant tip, tried it on my relatively new condor bushlore knife and it worked perfectly. I'm really pleased with it!

Ashley I wasn't criticising or passing judgement, just saying that I have a quick fix. I think the patina you have achieved looks great and gives an almost Damascus look to the blade. However I have tried the ketchup trick on an O1 steel blade and it's not touched it. Might have to try the vinegar soaked rag instead.

@Eagerbeaver - You should take more time to read articles; you don't need to warm the vinegar and I don't know how this "all seems a lot of effort" to you... it couldn't be easier? If you thought this article was a lot of effort - I wouldn't bother continuing to read the rest of the site.

This all seems a lot of effort. Try Ketchup for one hour. You can even apply it to just the edge or bits of the blade to give it a differential line. Easier than messing about with hot vinegar and making the house stink.

I have used this process on my knives with great success and i was very pleased with the final result

I used the vinegar method described above on an unfinnished blade made of 01 tool steel. It took two attempts to get the result i wanted but now its done it no longer looks unused. So cheers for the tip Ashley.

I've been getting into blade etching, darkening, adding patina for the knives I've been making, a good fast way to darken a blade to a dull grey colour is to fill a glass (long enough for your full blade to sit submerged in) with vinegar, then pour it into a small pot, get it simmering on the stove, then pour back into the glass. The hot vinegar works a LOT faster than room temp vinegar, and it produces a nice even result.

Tried downloading Form to Vote for NaturalBushcraft.co.uk for "Best Bushcraft Online Content" .... using link; each attempt at transferring data - it eventually says 'Stopped' each & every time!!!

I've used plain vegtable oil on a puukko and it's given it a patina. Figured it sorte oils it and still ok with food.

Multiple dabs of yellow mustard left on for a few hours will give good looking effect also.