The cause was found to be the result of an organometallic blue pigment which caused an exothermic catalytic reaction with another additive in the foam.
All reactions were found to proceed without an entrance barrier, to have exit barriers well below the energy of the reactant molecules and to be strongly exothermic.
Clearly, for both primed and control seeds, reactions were still occurring and resulting in an overall exothermic heat flow after seeds had lost the ability to germinate.
If we consider for example an upward propagating exothermic chemical reaction, then the temperature of the medium below the reaction zone is greater than the temperature above it.
In the case of propagating reaction fronts the exothermic chemical reaction plays the role of heating from below.
Neuronal responses are typically slow in cold conditions with consequences for the survival of exothermic organisms.
The reactions have no entrance barriers and are all exothermic.
This local maximum exists because the pressure behind the shock decreases as a result of the exothermic reaction and/or geometric expansion.