Popular with military and survival folks, and commonly available at any gear shop, magnesium/ferrocerium fire-starters are a standard outdoors tool.
They are cheap, reliable, and waterproof, and they are an alternative to matches or a Bic. Many outdoorsmen keep magnesium in their kit for “just in case” situations.
Scrape off a few shavings from the block onto dry grass or kindling — that’s your fuel. Turn the block around and strike the ferrocerium metal with the blade to shoot out sparks and light the metal tailings.
Once ignited with a spark, magnesium burns rapidly at a whopping 5,610 degrees Fahrenheit. Your leaves and grass will catch a flame, then you add twigs, sticks, and larger logs as the fire grows.
For this test we used the $5 Coghlans 7870, one of many similar products available. See the video tutorial and instructions below.
While the magnesium/ferrocerium method works, it’s hardly foolproof. Practice a few times in a controlled, safe situation before relying on this system in the woods.
Start A Fire With Magnesium
1. Prepare Fire Site. Pick a spot appropriate for a fire. Consider wind, precipitation, fire safety, and access to camping or cooking. Generally, it is best to use a pre-existing fire site in well-trafficked areas.
2. Collect Wood & Tinder. The base of your fire should be as dry as possible, such as bark from a dead tree. On that, you can build a tinder bunch using dry grass or twigs smaller than a match stick. Dry bark or sapwood also works well. Collect lots of small twigs and branches to grow the fire from infancy to a stable small blaze. Have a few larger, pinky-size sticks ready to add as the fire grows.
3. Shave Magnesium. Use any decent knife, preferably with a fixed or locking blade. Carefully shave or grind the magnesium into one place, ready to be added to the tinder. Wind will easily blow magnesium away, so try to work in a sheltered spot. Take your time and build up a decent pile about the size of a quarter.
4. Spark The Blaze. With the Coghlans and many other models, sparks are made on the opposite side of the magnesium block by rasping a blade against the embedded ferro rod. It’s best to control the sparks by moving the ferro up while holding the blade steady, but that is also easier said than done. Be careful not to upset your tinder and magnesium. Also easier said than done!
Tip: With some knives, you can use the back of the blade to spark the ferro or grind magnesium to save the honed edge from being dulled. (This method is common when using knives with a sharply squared-off back, some even designed with this purpose in mind.) In the video above, I use the front of the blade because the rounded backside of this knife does not throw sparks.
If using the back of a folding blade, close the knife first and use the exposed metal to shower sparks.
Many other metal objects, and in some cases even broken glass, can be used to make sparks.
It takes some force to get a good shower of sparks, so push hard. If using the cutting side of the blade, I prefer to use the back section, near the handle, as to not dull the more regularly used cutting edge toward the front.
Experiment carefully with ferro to get familiar with its characteristics, and remember, that blade is sharp.
5. Build Fire. When a spark falls on the magnesium, you will have a very hot, short-lived fire. Use it wisely, getting grass, small sticks and anything else flammable burning quickly. Once the flames are going, build the fire as any other.