[Types of splashing of blood drops when falling on various surfaces].

Aim of this study is to determine the influence of the surface irregularities on the presence and pattern of splashing in the area of the blood drop trace.Spraying of a freely falling drop of blood on various surfaces from a height of 10 to 150 cm was studied. It is suggested to distinguish primary and secondary spraying. Primary spraying is the result of the drop falling and its collision with the surface, the secondary spraying is caused by the second and subsequent drops falling into the formed trace, as well as by mechanical affect on the region of not fully dried, liquid blood. Satellite drops splashing should be evaluated separately. We received experimental blood traces from falling of the 40 μl drops on a smooth surface, smooth slightly fibrous surface and rough surface. It is established that when a drop falls on a smooth surface (glass), primary spraying is absent. Signs of spray appear on a flat, slightly fibrous surface (cardboard) when a drop falls from a height of 60 cm, on a rough surface (corrugated vinyl film) - from a height of 20 cm.