Figure 4. Height
distribution from the right side of the degrading bloodstains at various
timepoints (in minutes). The designated bin width was set to 5 µm.
Additionally, we observe a high degree of variance in the number of
observed cracks and pits; generally, for all stains, they increase
rapidly for the first 30 minutes and then they plateau (Figure 5).
Typical minute cracks around the edge of the bloodstain were not
detected by the profilometer, making it difficult to assess when crack
formation and propagation began, but it can be approximated to be
~15-20 minutes after deposition. Larger cracks located
towards the centre of the bloodstain appeared around 20-25 minutes after
deposition; surface average roughness values at these times slightly
increased. Earlier time points also contained more cracks and pits with
smaller areas which subsequently increased over time, leading to cracks
with larger areas at later time points (Supplemental S4). There does not
appear to be a volume dependence in this study as there is a high degree
of variance observed in these data.