SHC Part II: The Wick Effect

This is the continuation of the article “SHC Part I: The Strange Case of Mrs. Mary Hardy Reeser”.

What is Spontaneous Human Combustion (SHC)?

SHC is the phenomenon where a human being is incinerated without any known cause of external ignition. Rather, a chemical reaction from within the body causes it to burst into flames. The odd thing about SHC is that the torso and head are charred beyond recognition while, more frequently, the arms and legs of the body remain untouched by the flame as well as objects surrounding the victim. A greasy residue on the furniture and walls is often predominant in cases of SHC. There are also a rare handful of cases where the outside of the body has been charred and the organs are left unscathed by the fire.

SHC is not a very common occurrence. When it does happen, SHC strikes without warning and predominantly selects elderly women as its demographic of choice. Science has yet to determine the cause of SHC, but there is one theory that shows circumstances that could explain how a body can burn long and hot enough for fire to consume the body and leave the surrounding area relatively untouched. That theory is known as the Wick Effect.

The Wick Effect is a theory that suggests an external heat source, such as a smoldering cigarette or ember, begins a fire which then feeds off of the fatty tissues of the human body allowing the fire to burn much like a candle does. Much like a candle, in the wick effect, the victim’s body fat acts as the wax and the clothing or hair of the victim takes on the function of a wick. As the fatty tissue melts from the heat it is absorbed into the clothing and keeps the wick burning slowly. This theory explains why the bodies of SHC victims are utterly destroyed, but the surroundings are barely burned.

Supporters of this theory explain the remains of feet or hands through the existence of a temperature gradient– where the top of a burning object is hotter than the bottom (fire tends to go “up”). If the fire were on the bottom, it would lack the necessary airflow (bottom cool air to heated-by-flame air on top) to continue burning. In this respect, limbs that are lower on the body or extended away from the body do not burn easily and so they tend to be left untouched by flame. The Wick Effect theory also accounts for the greasy residue on the walls– it is the grease residue produced by the fatty tissue as it burns.

Though science hasn’t conclusively explained Spontaneous Human Combustion, most scientists agree that there is likely a reasonable explanation for the charred remains. A substantial number of the victims of SHC were smokers who appear to have died by falling asleep with a smoldering cigarette, cigar or pipe in hand. It is highly likely that such instances of death are not as coincidental as may be thought and, in fact, probably contribute to the cause of the fire. Still, until science explains with a certainty the origins of SHC, it will remain an unexplained phenomenon.