As you read about making knives you'll often see the term "heat treating". It's an integral part of knifemaking. If you make knives, you will heat-treat (or send your blades to someone who does). When you're just starting out in knifemaking (and especially if you are just considering taking the plunge), heat treating can be something of a mystery. I can remember, not so long ago, when the term gave me only vague images of flames and red-hot metal. So I decided to add this primer to explain a little about the process. What is heat treating? Simply put, heat treating is the magic that turns plain steel into knives. More scientifically, it's a metallurgical process that uses heat to alter the internal structure of the steel, making knives that cut better and last longer. Under the hood, heat treating is a complex process dealing with altering the crystalline structure of the metal, grain size and growth, etc. As you develop your skills as a knifemaker, you'll learn more about what's going on at the microscopic level. But for this short article, we'll keep things simple. For knifemakers, there are four stages of heat treating: Annealing - This is for softening hardened metal. If you want to make a knife from an old file, you'll need to anneal the file first so you can work it more easily. Normalizing - This is Valium for your steel. It relieves the stress in the metal that results from being abused during forging. Hardening - This is to make your steel a hard as it can be. Tempering - This is for mellowing out your hardened steel to keep it from being too rigid and brittle. Makers who forge their knives often make use of all these stages. Those of us who focus on stock removal mostly use Hardening and Tempering. In the next instalment, I'll look at how you can heat-treat your own blades.