Metals Guide: Patina vs. Rust

Let’s face it, all steel will rust eventually.

High carbon steel, stainless steel, all steel. It’s a natural process for a natural material.

High carbon tools, as the name implies, have a higher carbon content and very little chromium, which protects from rust. Stainless steel tools have a higher chromium content, protecting them for longer from corrosion but they are not invincible. It’s a myth that stainless steel can’t. It just takes longer. Though with abuse, prolonged exposure and lack of care, stainless steel will actually rust pretty fast. There are, however, ways to prevent your knife from rusting.

So let’s talk about what rust is, the steps we take to prevent our tools from rusting, and how you can prevent rust on your tools at home and in the field.

What is rust vs patina

Rust develops when the iron in steel reacts with oxygen and/or water. Rust is corrosion, and left unchecked, it can ruin your tool.

Rust is not patina. Through exposure to air, moisture, acids, and other substances, the surface of high carbon steel tools can develop a patina.  A patina can change color over time, even turning brown, yellow or black, but this isn’t the same thing as rust.

A patina actually protects the surface of a steel tool from rust and it adds a lot of great character. Some of our tools we actually expose to various acids to help build the patina for the aesthetic elements on purpose. 

How to prevent rust

We build quite a few of our tools out of high carbon steel, but we also take steps to limit corrosion and, ultimately, rust.

One way we treat our tools is by applying a patina with various acids. Another is to treat the surface with a black oxide, like Caswell’s, or other cold blue applications. This creates a barrier and protects the surface, just like an acid patina. However both options are not 100% going to solve the problem. 

The best way to prevent rust is to limit exposure to corrosive elements. So if you chop up some tomatoes, wash your tool with soap and water to clean the surface after use. Make sure you dry it off too!

Saltwater is one of the harshest corrosives you can expose your tools to. So please, if you like your tool at all, limit exposure and if it is exposed, clean and treat it promptly. 

Next consider applying a wax. We can recommend several waxes. 

If the tool is not going to be used for food prep, Renaissance Wax (a micro-crystaline wax polish) is a great option for a durable option. If the tool will be used around food, we like Axe Wax, made in Oregon.

Just follow the instructions of your favorite wax, and most importantly, reapply as needed to your clean tool. Also, it’s not a bad idea to wax your stainless steel tools too. Like we mentioned above, they are a metal too and can rust with the right conditions.

Another important note, make sure you keep the tool sheath clean and dry too. You can clean your tool all you want, but if you throw it into a sheath with a bunch of debris and moisture in it — whether that’s saltwater, sweat,  blood, or anything else, it’s going to cause the tool to rust.

Ready to invest in a Windy Raven tool? Our Foundation Series are a great starting spot. Made with stainless steel, these tools hold a great edge but are low maintenance.