How Can I Stop My Carbon Steel Knife From Rusting?

Last Updated: March 24, 2016

Carbon steel knives can be a beautiful pain in the ass sometimes. They are usually sharper, a dream to sharpen, and have amazing edge retention. Unfortunately, they can rust if not given a little extra care.


After a while the steel will oxidize and react with the air and start to change colour. Your knife will take on hues of grey, blue and black; this is a good thing. It means that a patina is on the way. Think of a patina as a little extra help in the war on rust.

Adam, who works in our Edmonton Knifewear, has figured out a pretty easy way to force an early patina onto a carbon steel.


What you’ll need:

-Cheap, pre-ground instant coffee. The cheaper the better, think of the coffee you'd get at 3:30 AM in a Gas Station. 

-A means to brew the awful coffee.

-A tall and slender vessel, like a flower vase.

-Your carbon steel knife

-A small sponge/dish cloth


Step 1: Brew that coffee!

-Brew a STRONG pot of coffee, so strong that you’d be jittery for days! Now chill it. You want the coffee to be cold for this process, we aren’t making a knife & coffee soup.


Step 2: Find a vessel for your knife

-Using your skinny & tall vessel, place the small sponge or dish cloth in the bottom. Put your knife in gently, tip down. 

-Pour in the chilled coffee until it covers the entire blade of your knife, but does NOT submerge the handle.

-Leave the knife in the solution for 6-8 hours minimum. Overnight is ideal.


Step 3:Check out my Shimo Santoku alongside a brand new one! Pretty amazing huh?
After the recommended amount of time has passed, take the knife out of the coffee and wipe down with a damp cloth and dry thoroughly. Your knife has undergone an incredible transformation and is now a lot easier to maintain. Still wipe that blade down and keep it clean and dry, but it’s going to be a lot more rust resistant than before.


Step 4 (Optional but suggested):
You want to get that coffee smell off the steel, so I recommend cutting up some yellow onions to pull out the coffee fragrance. Then fry those onions with some bacon and put ‘em on a burger. You can thank me later by making a burger for me too.


Pretty cool, huh? This process produces spectacular results on Shirogami #1 or #2 AND Aogami #2, my Moritaka is jet black.


Chris Lord

Chris Lord


Chris is a relocated Maritimer that can be found slinking in and out the back doors of Ottawa's restaurants, often with his daughter in tow. Chris has been a fixture in the Ottawa food scene for the past 10 years and has recently laid down his apron to learn the ways of Knifewear. Chris loves cooking big pieces of meat over a live fire and spends his summer feeding wood into his BBQ, Lemmy Smoke-mister.