By John Thompson
LET THOSE TOOLS RUST!!!
That four letter word that sends chills down the spine of any tool collector. Rust is the disease that spreads through those prized tools and ultimately destroys their value and function…… But what if I told you that rust can protect your tool !?!? We have to take a closer look at rust and what it is, what it does to our tools, and why it does it to them in order understand how it can be helpful.
First thing that pops into peoples mind’s when you say rust is that orange/brown flakey stuff that makes pits and holes in the metal of a tool. When metal rusts it is being oxidized, or the metal is taking in oxygen and forming a new compound. For example, Iron (Fe+) is turned into some form of FeO (iron oxide). Fe2O3 or ferric iron( the nasty Red stuff) is the compound most of us are familiar with as being the source of our frustration. While this is one of many possible compounds formed, there are several other possible forms of rust that can occur, but most of them have little importance to the scope or point of this article. The other form of rust we are interested in and most people aren’t aware of is the Fe3O4 or black rust. Black rust is also known as magnetite. Magnetite is a form of rust that has similar physical properties to the original metal such as being magnetic and more importantly for us it’s solid. For us tool nuts, we know it by a different name……Patina! To a collector of fine tools Patina is as valuable and beautiful as gold. So why is this type of rust good and desirable and the red rust not? Black rust forms a protective barrier that keeps the metal from oxidizing (or bad rusting) further, not to mention it looks cool! Patina gives the tool a look of distinction and age. It can take dozens or even hundreds of years for Patina to form which gives the tool the appearance of a beautiful antique.
So what’s the difference in how these two rust types form and how do we get Patina to form rather than Red rust? The main ingredient that is absent when Black rust forms is water. Water acts as a catalyst (fancy word for facilitator) to Red rust and speeds up the oxidation process. Most metals are porous to some degree and it’s these pores that allow water to get into the metal, help oxidize it, and turn solid metal to flakey Red rust. If you have ever sanded metal to bright and shiny appearance and literally watched the rust start to form almost immediately, then you how fast this process can be. As the water gets further into the metal, holes or pits are created. Black rust (unlike its demonic brother Red rust) forms a solid coating that is just as hard as the original metal. This coating keeps the metal behind it from oxidizing or rusting further essentially preserving the tool!
Black rust is a fantastic thing, not only to look at but for protection of the tool. Unfortunately, it take A LONG time for it to form, not to mention how rare it occurs that a tool has been kept completely away from moisture its entire life. These are the main reasons Patina is so prized. So before you take a piece of sandpaper and make that tool shiny again, make sure you want to remove more than just the color of the tool…….but feel free to go to town on the Red stuff!