High-speed photography of blood drops impacting different target surfaces …show more content…
This was however not the case for wallpaper where the blood could be seen moving up and down the bloodstain before finally forming the bloodstain. This may have been due to the amount of friction the blood encountered when moving along the surface – there would not have been much friction force in the case of the cardboard, however on the wallpaper, because it is a textured surface, there would have been a greater friction force. Given this finding, it would have been expected that the time taken for a bloodstain to form on the wood surface would have taken approximately the same time as the time taken for a bloodstain to form on wallpaper. This was however not the case, with the bloodstain forming in only 39.6 ms on wood. It was seen in the high-speed video of a bloodstain forming on wood that the blood travelled continuously in a downward direction meaning no extra time was spent with blood moving up and down the bloodstain. The bloodstains that took the shortest amount of time to form had the longest wave