Building a Fire

5-8. Once the fire site is selected and prepared, the fire-building process can begin. The first step is to procure a base and a brace (see figure 5-3 on page 5-4) which are used to initially establish and control the fire. The base is a flat piece of material, usually wood or a nonporous rock (porous rocks contain water and, when heated, can explode). The base is used to keep moisture susceptible tinder and kindling off the wet ground and provides a clear area to skillfully ignite tinder. The brace is employed across the base to help control oxygen into either the tinder, kindling, or fuel being worked. It is about the size of a person’s forearm. A broken branch can typically be found and employed as a brace.

Figure 5-3. Base and brace

5-9. After preparing the base and brace, fuel is procured and prepared to start and maintain the fire. Fire building occurs across 3 phases. If one phase is skipped even in ideal circumstances, it is likely that the fire will fail due to not having the appropriate mix of oxygen, heat, and fuel. The 3 phases are tinder, kindling, and fuel, each representing an increase in fuel size appropriate for heat and oxygen available to support it. Figure 5-4 provides examples of tinder, kindling, and fuel.

Figure 5-4. Tinder and kindling examples

Tinder

5-10. Tinder is used during the first phase of fire building. A dry material can be ignited by a small spark, coal, or flame. Tinder is normally comprised of fine fibers or is petroleum-based and is either natural or manmade. Isolated persons can procure natural tinder, when damp, and store it between layers of clothing to use heat radiated by the body to dry it prior to use. When using fibrous tinder to start a single fire, isolated persons collect enough to fill their hand with fingers cupped. Natural tinder examples include—

  • Birch bark—shredded inner bark known as heartwood from cedar, chestnut, red elm trees.
  • Fine wood scrapings or shavings (heartwood preferred).
  • Dead dry grass, ferns, moss, lichen, and fungi.
  • Dry powdered sap from the pine tree family also known as pitch.
  • Fine pitch wood scrapings or shavings.
  • Crushed fibers from a dead plant.
  • Pine pitch globules mixed with fibrous material.
  • Seed down (milkweed, cattail, thistle).
  • Feather sticks (wood shavings cut into and still connected to a piece of wood).

5-11. Manmade tinder examples include—

  • Cotton balls (most effective when coated with a petroleum-based paste).
  • Lint.
  • Paper
  • Foam rubber.
  • Hexamine.
  • Tryoxine.
  • Commercial petroleum-based pastes.
  • Steel wool.
  • Gunpowder.
  • Candle.
  • Solid-state fuel tabs.

5-12. Isolated persons can procure natural tinder, when damp, and store it between layers of clothing to use heat radiated by the body to dry it prior to use. When using fibrous tinder to start a single fire, isolated persons collect enough to fill their patrol cap or their hand with fingers cupped at a minimum. A sufficient amount of tinder must be used to generate a hot enough flame to ignite kindling in the next phase of fire building. Smaller quantities of petroleum-based products are used as they burn much longer with a central burn point. To ignite some petroleum-based tinder such as tree sap, it may be necessary to combine it with some fibrous tinder to catch the flame for ignition.

5-13. Tinder is laid on a dry base to avoid the fine fibers from soaking up moisture and rendering it unusable. When laid on the base it rests up against the brace in a mound. The tinder is lighted from its bottom edge away from the brace. The initial flame is small and is most easily able to spread in an upward sloping direction creating a more reliable, quicker, and hotter flame to engulf the tinder and ignite kindling.

Kindling

5-14. Kindling is the second phase of fire building. Kindling is added once the tinder is burning strong and mostly engulfed by flame. It is laid by the handful on, and perpendicular to, the top of the brace and over the burning tinder. It should be laid over the tinder fire so that some spaces are left in the kindling for the tinder fire to burn through. If the kindling is laid over the tinder like a blanket, the fire will likely not receive enough oxygen to continue burning, will not be able to ignite the kindling, and will die out. The second handful of kindling is laid perpendicular or diagonal to the first laid kindling to maintain small pockets for the fire to burn through and grow.

5-15. Kindling has a high combustible point similar to tinder. The kindling phase is used to transition to large long burning fuel by increasing the size of the fire, and creating an initial coal base that increases heat output and the fire’s longevity.

5-16. Examples of kindling include—

  • Dead, dry, small twigs and plant stalks; isolated persons should consider that during the winter months live deciduous vegetation that is dormant may appear dead. A quick check of the cambium layer—just under the bark—will indicate whether it is alive or dead.
  • Dead, dry, thinly shaved pieces of wood, bamboo, or cane (always split bamboo as sections can explode).
  • Dead coniferous needles.
  • Small branches low to the ground on the underside of coniferous trees that are dead from lack of sun (a single branch often has all three sizes of kindling on it that simply need to be broken down for use).
  • Some plastics such as the spoon from an in-flight ration.
  • Wood which has been soaked or doused with flammable materials; that is, wax, insect repellent, petroleum fuels, or oil.
  • Strips of petrolatum gauze from a first aid kit.
  • Pitch wood sticks.
  • Larger pieces of wood split into kindling-sized pieces.

5-17. The inner wood of dead branches and small diameter trees is the driest because it is not exposed to the weather. Wood that is split to expose the inner wood grains burns faster and hotter than wood pieces that are covered by bark which naturally protects trees from fire and collects moisture. Wood less than 3 inches in diameter and approximately 1 to 2 feet in length can easily be split using a strong fixed blade survival knife and a sturdy forearm sized branch. The branch is used to drive the knife down the length of the wood along the grain. Wood with the fewest knots is selected for splitting. The split is repeated until the desired size is reached.

5-18. The following method is used to split wood with a fixed blade survival knife:

  • Step 1. Set the piece to be split upright on the ground, or on a sturdy base, and hold it in position.
  • Step 2. In the non-primary hand, hold the knife, blade down, on the top of the wood piece, the tip should extend well past the edge of wood and slightly into the air so that the knife is at about a 60-degree angle to the wood piece.
  • Step 3. Place pressure on the handle of the knife to ensure the blow of the branch onto the tip end of the knife drives the blade into the wood (if proper pressure is not applied the energy from the blow will instead result in popping the handle into the air)
  • Step 4. Strike a blow with the branch against the tip end of the knife.
  • Step 5. Repeat until the wood piece is split through; continue splitting each piece into smaller pieces to reach the desired size.

5-19. Preparing kindling in several different sizes that range from pencil lead, to pencil, and then to thumb size will make fire-building easy when laid over the tinder in that order. Kindling that is approximately 12 to 18 inches in length is the easiest to apply and manipulate when building a fire. Isolated persons collect at the very minimum; the diameter of a soda can of each size, to ensure enough kindling is available to increase the fire’s heat to ignite the fuel in the next phase.

Fuel

5-20. Wood used as fuel should be the diameter of the forearm at a minimum. Wood is the most abundant source of fuel in most environments; however, there are many other types of fuel an isolated person can use. Unlike tinder and kindling, fire fuel does not have to be kept completely dry if the fire is established well enough to dry the damp fuel before burning. However, the more moisture fuel contains the more white smoke the fire will produced as it burns it off. The type of fuel will determine the amount of heat and light the fire produces. Dry, split hardwood trees (such as oak, hickory, and ash) are less likely to produce excessive smoke and provide more heat than softwoods (pine, spruce, and fir) due to their higher density. This density however makes them more difficult to break and split into usable pieces than softwood. Softwood burns faster and produces more smoke unless a large flame is maintained. They are often straight grained, have fewer knots, and are easy to split.

5-21. .Effective fuel sources include dry, standing, dead wood and dry, dead branches (those that snap when broken). Standing or leaning dead wood is usually dry even in rainy climates as its vertical position sheds most rain. In contrast, rotten wood, most of which is found lying directly on the ground, is of little use since it smolders and is very difficult to ignite. It produces a large amount of smoke, which can be useful in a signaling situation, but is a poor fuel.

Caution. Highly flammable liquids should not be poured on an existing fire. Even a smoldering fire can cause liquids to explode and cause serious burns.

5-22. Dead wood is easy to split and break. It can be pounded on a rock or wedged between trees 2 to 3 feet apart, bending it until it breaks. A large survival knife can also be used to split the wood to reach the heartwood, which is typically the last to rot. As a last resort green wood, which is found almost anywhere, can be made to burn if finely split and mixed evenly with dry, dead wood. In extremely cold weather, moisture is pulled from green wood, which then becomes a viable fuel. Wood used as fuel must be free of poisonous plants such as poison ivy or poison oak. These plants can cause respiratory distress if burned and inhaled. In areas void of wood, other fuels can be used:

  • Dry grasses can be twisted into bunches.
  • Dry bamboo can be used as a fuel after it is split to open its sections; isolated persons must beware of large splitters.
  • Dead cactus and other plants are available in deserts.
  • Dry peat moss can be found along the surface of undercut stream banks and in dry swampy areas.
  • Dried animal dung, animal fats, and sometimes-even coal can be used as fuel if located.
  • Blubber from marine animals can be used as a fuel source.
  • Oil, diesel, gasoline, and other high-performance fuels can be used when mixed with sand to slow their burn rate and prolong their burn time. This makes them a safe fuel alternative.
  • Vehicle tires burn well but are difficult to ignite and may produce chemicals that should not be inhaled.

Caution. Petroleum-based fuels will produce thick, black smoke when burned. Inhaled petroleum products can be harmful to the health and respiratory system of the isolated person. Do not prepare foods directly over petroleum-based fires due to the toxins produced. Ensure proper ventilation when utilizing these types of fuels.

Fire Lays

5-23. Isolated persons lay the fuel in a manner consistent with their purpose as listed in paragraph 5-1. A fire lay is a structure constructed by the manner in which fuel, typically wood, is placed to focus heat or flame, accommodate personnel, provide light, or use fuel. Selecting the correct fire lay to support specific tasks will make the fire a more effective and efficient tool. Commonly used fire lays include—

Tepee

5-24. Tepee fires are made by arranging the tinder and a few sticks of kindling in the shape of a tepee or cone. The center can be lighted after the structure is built or the structure can be built around a small fire. As the tepee burns, the outside logs will fall inward, feeding the fire. This type of fire burns well even with wet wood. (See figure 5-5 on page 5-9 for an example).

Lean-to

5-25. Lean-to fires are constructed by pushing a green stick into the ground at a 30-degree angle. The end of the stick is pointed in the direction of the wind. Tinder is placed deep under the lean-to stick. Kindling is then placed against the lean-to stick. The tinder is then lighted. As the kindling catches fire from the tinder, more kindling and later fuel, is added. (See figure 5-5 on page 5-9 for an example).

Cross-ditch

5-26. Cross-ditch fires are constructed by digging an “X” about 12 inches in diameter, and 3 inches deep into the ground. Tinder is placed in the middle of the cross. A kindling pyramid is built above the tinder. The shallow ditch allows air to sweep under the tinder to provide a draft. (See figure 5-5 on page 5-9 for an example).

Pyramid

5-27. A pyramid fire is built by placing two small logs or branches parallel on the ground. A solid layer of small logs are then set across the parallel logs to make a platform. Three or four more layers of logs are added, each layer smaller than the last and perpendicular to the layer below it. A starter fire is then built on top of the pyramid. As the starter fire burns, it will ignite the logs below it. This creates a fire that burns downward, requiring no attention during the night. (See figure 5-5 on page 5-9 for an example).

Log Cabin

5-28. As the name implies, this lay looks similar to a log cabin. Log cabin fires are built by placing layers upon layers of perpendicular fuel wood. This fire creates a great amount of light and heat, primarily because of the amount of oxygen which enters the fire. The log cabin fire creates a quick and large bed of coals and can be used for cooking or as the basis for a signal fire.

Long Fire

5-29. The long fire can be made as a trench, the length of which is laid to take advantage of existing wind. It can also be built above ground by dragging two logs (green is better) parallel to each other to hold the coals together. These logs should be at least 6 inches in diameter and situated so cooking utensils can rest upon the logs. Two 1-inch-thick sticks can be placed under both logs, one at each end of the long fire. This is done to allow the coals to receive more air. Long fires allow larger groups of personnel near the heat and enable coals to be moved to one end for cooking with a fire at the other.

Star Fire

5-30. Star fires are built by placing wood pieces or logs in the shape of spokes in a wheel so that the inner ends burn in the fire. As the ends burn, the remaining fuel from each log is pulled closer to the fire. The star fire is used when conservation of fuel is necessary or a small fire is desired. It also allows isolated persons to use larger pieces of fuel that they can otherwise not break down into smaller pieces suitable for other fire lays. This fire must be constantly tended. Hardwood fuels work best for star fires.

Figure 5-5. Fire lays

5-31. When completed with a fire it is extinguished using materials such as water, entrenching tools, dirt or sand, and sturdy sticks that are prepared in advance. A fire is extinguished by removing one of the fire triangle elements. Fires with nonpetroleum-based fuel can be extinguished with an adequate amount of water. Large pieces of burning wood can be separated and the coals can be raked off with a tree branch. Some burning fuel can be broken apart and scattered over bare soils. Dirt or sand works well to extinguish petroleum-based fires. Isolated persons may even be able to retrieve a chemical-based fire extinguisher from their aircraft or vehicle for this purpose.

CAUTION.
When leaving an area after having a fire, ensure that the ground under where the fire was built is cool to the touch.

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