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Fire Piston
Ignition by rapid compression using a thermodynamic device. Similar to a diesel engine, the fire piston creates a spark by rapid compression of a gas. In thermodynamics this process is called adiabatic compression. When the pressure of a gas is increased from work done on it by its surroundings such as a fire piston, adiabatic heating is achieved. The fire piston relies on the same principle as the diesel engine to ignite the fuel in the cylinder. Diesel engines do not use a spark plug. Instead the diesel engine uses the the heating which occurs during their compression stroke to raise the temperature sufficiently to ignite the fuel.
The origins of the fire piston are from South East Asia.
We used stainless steel pipe and bolts to build this fire piston. The stainless steel is a fair thermal insulator. Most fire pistons are made of wood. (Cocobolo wood)
We used Chaga fungus / mushroom (Inonotus obliquus), called by many names: Clinker Fungus, Cinder Conk, Birch Canker Polypore, Black Mass, Sterile Conk Trunk Rot of Birch. Besides it being an amazing spark catcher tinder, the fungus is used by many for medicinal purposes.
The fire piston is limited to certain types of tinder:
* Chaga fungus
* Char cloth (Charred Cloth)
* punk wood
* Cattail fluff
* Dandelion clock
* Poplar cotton
* Amadou
* Rosebay Willowherb fluff
* Char paper (Charred paper)
We place a small piece of the tinder fungus on the end of the piston. We quickly compress the fire piston and pull it back out. Sometimes the tinder will simply char after the first try. This can be caused by the material type or humidity level in both the tinder and air. We usually blow softly on the tinder after compression and it should burn brighter.
Once we get the coal burning steadily, we remove it using a knife. For this article, I added another piece of the Chaga fungus to make the coal larger. At this point we would want to ignite the tinder as with any other fire starting method described on the site. We take the small coal and place it on another material that will help keep it burning. In this instance, we used Cattail fluff.
We place the Chaga fungus into the Cattail fluff. Wrap the coal using a tinder nest. We used dry grass and Cattail leaves. Slowly and steadily blow on the coal until it heats up and it becomes brighter. At that point, I usually prefer to add more oxygen and it should ignite. If the wind is blowing strong, it is usually enough to ignite it.
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