Eastern Kentucky University, USA
The investigation of hay fires has long been a challenge for the fire service. Fires of this type are notoriously difficult to extinguish and usually require allowing the fire to run out of fuel (or the use of heavy equipment and large volumes of water). Inherently, this creates a “black hole” for fire investigators as they are often left with little more than witness statements to base their conclusions on. As a result, many hay fires are attributed to spontaneous combustion for lack of a better explanation. One of the traditional indicators of spontaneous combustion that fire investigators have relied upon in the past is the formation and/or presence of hay clinkers. Several reliable sources indicate the formation of hay clinkers is an event which is mutually exclusive to spontaneous combustion. After a string of suspicious cases in which hay clinkers were discovered, the Tennessee Department of Agriculture’s Criminal Investigation Division conducted a series of field tests. The results of these field tests indicate that hay clinker production is possible with an external ignition source and should not be utilized as an indicator of fire cause.