How To Use Fire As A Tool

Fire has a number of uses in the wilderness. Among many other things, it can generate heat, boil water, and summon rescue. But have you ever used fire as a “tool”? Fire has the amazing ability to consume materials, as well as to modify them. Here are three uses for fire that you might not have considered.

Fire Hardening Wood And Bone
Fire hardening is a frequently misunderstood concept. Most people think that fire hardens wood and bone by somehow changing the structure of the material, but fire hardening is simply the act of “super drying” the material in question. When wood and bone are moist, they are soft. When they’re dry, they are harder.

To fire harden them, simply dry them over a fire just above the flames. Bone is ready as soon as it starts to turn tan, wood when it achieves a toasted color. Plant or animal oil can be rubbed on whatever you are hardening before and/or after the hardening process. Sharpen points on pieces of wood and bone both before hardening, and then again after.

Thermal Alteration Of Stone
Many cultures, including a great number of Native Americans, have used heat to alter stone for sharper arrowheads and knives. Typically, the stone is broken (the technical term is spalled) into large flakes, placed in sand and then a fire is burned over the sand to heat the stone. Once the stone gets hot enough, it becomes more “glasslike.” This heat treating will yield stone that breaks with a sharper edge. Many other techniques exist for thermal alteration, but all produce highly variable results. If you’re learning how to make arrowheads, for example, heat treating can make inferior stones into useable practice materials. You’ll also see some really neat, often unexpected colors emerge from the stone.

Heat Bending Wood
Heat bending can straighten a crooked stick, or bend a straight one. The moisture in a green wood stick, or a dry wood plank that has been soaked in water for a few days, causes the wood to become flexible after “cooking” it over a fire. To do this, simply rotate the moist wood item over the fire and begin to bend it gently. The wood should begin to feel rubbery when it is heated enough. But be careful not to blacken or scorch the wood, as this will weaken it. Bend the wood a little beyond the point you are trying to achieve, and then hold it in that position until it has thoroughly cooled. If the bend will not take, reheat and keep working the wood. Heat bending is very useful in bow making, especially when making recurves.

Have you had experience with one of these methods? Tell us about it in the comments.