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John McCann

Cold Weather Survival: 5 Heat Loss Mechanisms

Body-Heat-Loss-Infographic

Learn the five ways your body loses heat in this cold weather survival feature. Addressing these heat loss mechanisms will go a long way in cold weather.

The ways that heat from your body can be transferred to the environment are called heat loss mechanisms. In a hot climate some of these mechanisms can be used to your advantage, but in a cold weather survival scenario they can all be detrimental.

#1 Heat Loss Mechanism: Radiation

Radiation is the primary cause of heat loss. Our body radiates heat to the environment much like the sun radiates heat to the earth or a campfire radiates heat to keep us warm.

At 50 degrees F, 50 percent of the body’s heat can be transferred to the environment through an exposed head and neck. We can also lose heat from our wrists, hands and feet.

#2 Heat Loss Mechanism: Conduction

Conduction is the process by which we lose heat through direct contact between objects. This can occur when sitting on a cold or snow-covered stump or rock, when wet clothes come in contact with your body, by touching cold objects with bare hands, or by kneeling on the snow to build an emergency shelter. Avoid these situations to prevent conduction of heat from the body to other objects.

#3 Heat Loss Mechanism: Convection

Convection is loss of body heat due to movement of air or liquid across your skin. An example of convection is wind chill. Through radiation, the human body is always warming a thin layer of air next to the skin. The temperature of that layer of air is usually equal to that of the skin. When this layer of warm air is undisturbed, the body stays warm. However, if this warm layer is removed by convection, the body quickly cools down.

#4 Heat Loss Mechanism: Evaporation

Evaporation is a process whereby liquid changes to vapor, during which heat from the liquid escapes to the environment. In a cold environment, it is essential to wear fabrics that breathe. If water vapor from perspiration cannot evaporate through clothing, it will condense, freeze and reduce the insulation value of the clothing. This will cause your body temperature to go down.

#5 Heat Loss Mechanism: Respiration

We lose heat through our normal breathing process. You can observe this when you see a person’s breath on a cold day. This is heat from the body lost to the environment. It is also difficult to prevent this loss, as we have to breathe.

Demystified: Ferrocerium and Mischmetal Fire Starter Rods

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Ferrocerium-and-Mischmetal-Fire-Starter-Rods

I would like to attempt to clarify the confusion often surrounding the terms “ferrocerium” and “mischmetal” when it comes to various fire starters.

My wife, who speaks fluent German, voiced confusion to the term mischmetal as it relates to ferrocerium. She explained that the term mischmetal is from the German word Mishmetall, meaning mixed metal, and that since a ferrocerium rod is made of a mixture of metal, by definition it is a mischmetal rod.

So I did a little digging and she is right. But the terms have taken on their own vernacular by the survival/fire-starting community. The terms are used to distinguish the difference between two types of fire-starting rods or tools.

What are Mischmetal and Ferrocerium?

A mischmetal, also known as cerium mischmetal, is an alloy of rare earth elements, namely those from the lanthanum series. The resultant mischmetal by itself is too soft to use as a flint, such as used in a lighter.

Therefore, it is blended with iron oxide and magnesium oxide. The resulting man-made material is called ferrocerium — probably because of the addition of the iron (ferro) and the mischmetal (cerium), hence ferrocerium—and will produce sparks to ignite tinder when scraped by a sharp edge, usually a piece of steel.

The scraper is called a striker. For years, this was the only type of spark-producing fire-starting device that came in a rod form, and was termed a ferrocerium rod or a mischmetal fire starter.

The New Mischmetal Rod

Enter the twenty-first century and a desire for a hotter fire starter rod. A new fire starter rod is introduced and it is called a mischmetal rod. I know, I know, but what can I say.

This rod allows the user to obtain both a sufficient ignition spark and an ample shower of hot burning flakes of magnesium used to ignite tinder.

Without getting too technical, this is done by lowering the iron content and increasing the magnesium content. The increased amount of magnesium, relative to the decreased iron content, results in a softer rod.

The pieces that are scraped off are larger and, after being ignited by the sparks, continue to burn after leaving the rod.

Which One is Right for You?

There you have it. For the purpose of this book, a ferrocerium rod (also known as a ferro rod) is harder and gives lots of sparks, but the sparks don’t continue to burn.

A mischmetal rod gives large burning chunks of magnesium that continue to burn after leaving the rod.

I, being old school, still prefer the ferrocerium rod. It is hard and, in my opinion, lasts much longer than a mischmetal rod. A ferro rod only gives you sparks, but hot sparks, and they have always been adequate for me to ignite tinder. The sparks are fairly easy to aim into a tinder pile.

I have found that the large burning pieces of magnesium scraped off the mischmetal rod are more difficult to aim and the rods wear down in a much shorter time than a ferro rod.

However, when the hot burning pieces of magnesium do find their way into the tinder, they burn longer, and will even ignite a piece of paper (a ferro rod won’t do that).

To make an intelligent decision, experiment with both and determine which is best for you.

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