Drying Times
The following pictures are blood drops released from approximately 36" above a ceramic tile floor and allowed to dry at various time intervals. There are variables to consider when estimating drying times of blood such as the surface on which the blood is on, current temperatures and any contributing factors like a fan, air vents or possibly a window open. The current temperature for this experiment was approximately 72 degrees. All stains were wiped from left to right with an index card. Notice, that over the time intervals, the stains begin to form rings as the blood dries from the outside inward. Knowing the drying times of blood and the variables which can affect drying times can help in determining the sequence of events which transpired, as well as refute or collaborate a suspects statement.
30 seconds
2 minutes
5 minutes
20 minutes
30 minutes
The following test was done to see how fast a drop of blood measuring at .88mm X .80mm would dry. The temperature was 70 degrees and the humidity was approx. 52%. At twenty minutes I touched the drop with a tissue and found no visible transfer. I suspect, however, that it dried prior to twenty minutes. I believe it dried between 13 and twenty minutes. Yes, those are fingerprint ridges (my left index to be exact).
1 Minutes at approx. 100x 5 Minutes at approx. 100x
10 Minutes at approx. 100x 13 Minutes at approx. 100x
15 Minutes at approx. 100x 20 Minutes (Dry) at approx. 100x
20 Minutes (verified dryness by rubbing-started to crack) apprx. 100x