Collecting Prints on Porous and Non-Porous Surfaces
Introduction
To begin with, I would like to say that I found this experiment extremely engaging and interesting. I was able to identify numerous prints on various surfaces, analyze how the marks are different from each other, and see how the porousness of surfaces affects the visibility of marks. Overall, I managed to locate a total of ten different prints, four of which were partial. There was a variety of objects and surfaces I selected for the experiment, including a paper plate (one print), a car window (one print), and a cardboard warranty card (four prints). Partial marks, one on each surface, were located on a microwave, a paper plate, a soda can, and a freezer. Finally, I also selected some other objects like a telephone, a plastic dog gate, a backdoor handle, and a refrigerator, but they contained only non-usable prints. All these objects and surfaces were located in various parts of my house.
Discussion
To locate and lift the prints, I used a fiberglass filament brush, a fingerprint lifting tape, and latent print powder (black volcano latent print powder). I also wore gloves not to leave additional prints during the process (CSInetwork, 2010). First of all, I took the fingerprint brush, dipped it into the latent print powder, and knocked the surplus powder off the brush, as recommended by lecturer Phil Gilhooley (Liverpool John Moores University, 2011). Then, I used a back-and-forth half-circle motion while holding the brush end with my index finger, middle finger, and thumb to see partial or whole prints. Finally, the fingerprint lifting tape helped me to lift the prints and analyze their similarities and differences.
Overall, it is challenging for me to say whether I expected to find more or fewer prints. It would probably be more engaging to locate several whole or partial marks, which is what I wanted to achieve. At the same time, I knew that there had to be various types of surfaces, and the porousness or non-porousness of some of them would affect the experiment. I would also like to note that I managed to spot some differences between the prints. For instance, they vary in size and visibility because of deposition pressure, which is a rather important factor. Thus, it is possible to suggest that more pressure was applied when leaving fingerprints on the paper plate than on the car window. However, what I failed in is the certain identification of the main print types like arch, loop, and whorl. I think that I needed to pay specific attention to removing excess powder from the prints so that it does not remain in the ridges (Liverpool John Moores University, 2011). Finally, as for the porous and non-porous items, the former group contains the car window, the microwave, the soda can, the freezer, the metal door handle, the telephone, and the plastic dog gate. Non-porous surfaces I selected are the paper plate, the cardboard warranty card, the backdoor handle, and the refrigerator.
In this part of the assignment, I received an opportunity to observe how different water temperatures and structures affect the visibility of latent prints left on a non-porous object. Overall, I conducted four experiments with the same glass drinking cup. The first experiment included cold tap water: I left some fingerprints on the cup and immersed it in water for three hours. After that, I noticed that prints became more visible, and this observation is supported by Trapecar (2012) and Ibrahim (2017), who state that cold water helps to recover finger marks. Then, before conducting the hot water experiment, I had to use the latent print powder to enhance the visual of the prints on the glass to determine if the marks faded or not. After the cup remained in hot water for three hours, the prints remained intact. I may suppose that if I never used the powder, finger marks would not be as visible on the heated glass. The reason is that, as stated by researchers, fingerprints are made of water and oil (Ibrahim, 2017). Consequently, after an object is submerged in hot water, prints become less visible.
Conclusion
Further, I started the third experiment and used salted water. The time the glass spent in the water was again three hours, and it contained the same prints covered with latent black powder. After I removed the glass cup, I noticed that most of the fingerprints that remained visible following the first and second experiments disappeared. However, some visible marks remained, and this is supported by Kallumpurat and Kudtarkar (2018), who prove in their study that “the salinity of the water has a destructive effect on the quality of print developed” (p. 001). Finally, the last experiment I conducted was with soapy water (I used Dawn Ultra Platinum Powerwash). Again, I took the same glass cup with the remaining fingerprints, and the time it was in water equals three hours. What I managed to notice was that finger marks became slightly less visible as the soapy water was able to wash away the layers of oil and water that make up the prints. As a result, this task allowed me to learn that compared with cold water, which enhances the visibility of marks, hot, salt, and soapy water makes fingerprints less noticeable.
References
CSInetwork. (2010). Developing latent fingerprints with black powder [Video]. YouTube. Web.
Ibrahim, S. M. (2017). California state science fair 2017 project summary [PDF document]. Web.
Kallumpurat, A., & Kudtarkar, A. (2018). Development of latent finger prints from porous and non-porous substances disposed in water. Journal of Forensic Science & Criminal Investigation, 10(1), 001-0012.
Liverpool John Moores University. (2011). How to dust for fingerprints [Video]. YouTube. Web.
Trapecar, M. (2012). Finger marks on glass and metal surfaces recovered from stagnant water. Egyptian Journal of Forensic Sciences, 2(2), 48-53.