The “Patina” Explained and a Guide to Do It Yourself
A patina is a naturally occurring thin layer of oxidization on your blade. It’s caused by various chemical compounds reacting with your steel. It will happen over time and with use—you’ll notice different colours and textures on your blade—particularly after cutting acidic fruits and vegetables. Have you ever seen how copper will turn green after time? (show parliament buildings) This is a natural patina.
The patina, though a form of rust, ironically protects the blade and adds a layer of protecting against deeper corrosion. Because it’s a controlled oxidization, it’s a similar process to rusting, but to a lesser degree. The patina will come out charcoal grey and its shade will depend on how long you apply the acid. On top of the added protection, many people like the look of a forced patina.
To “force a patina” is to manually quicken this natural process. Because a stainless steel blade is already protected with chromium, you’ll only want to apply a patina to your carbon steel blades. It’s achieved by exposing the blade to certain acids: vinegar or mustard generally have good results. You can soak your blade directly in the acid (be careful of your handle and epoxy) or wrap your blade in a towel soaked in vinegar. You can get arts-and-craftsy here and play around with different materials, solutions, and designs.
Many knife makers will heat up the vinegar in a pot or microwave before submerging their knife (consider using a coat hander to help dip it). Experiment with soak times as you watch the patina develop. Don’t worry too much about the particulars, you can always reapply or wash off the patina and try again.
Once you’re satisfied with the look, thoroughly clean, rinse, and dry your blade off. Windex is helpful for removing the leftover acid.
Like the look? Send me a picture of the finished result! 🙂
- Source  – http://tbwpodcast.com/knife-patina-how-to-do/
- Source  – https://en.wikipedia.org/wiki/Patina#Acquired_patina
- Source  – http://www.thetruthaboutknives.com/2014/07/ask-a-knifemaker-the-truth-about-rust/
- Source  – https://www.cooksillustrated.com/how_tos/8900-carbon-steel-knives-why-a-patina-matters