Fingerprint analysis is the oldest and common form of forensic evidence and unique of each individual. There are two types of finger prints –patent and latent. Patent fingerprints are easily visible to the naked eye and are caused by inks, blood, oil or paint ("A Simplified Guide To Fingerprint Analysis", 2017). Latent ones are not visible to the naked eye and are caused by skin secretions like oil and sweat (Daluz, n.d.). There are various ways of experimenting the latent fingerprints depending on the surface, material, temperature and chemicals. Here we will study the effect of different temperatures (hot and cold water) and different chemicals (salt and soapy water)
Experiment
The materials required for the experiment are a drinking glass, a bowl filed with normal temperature water i.e. tap water, ice cubes to reduce the temperature of water, gloves, wipes. I have done the experiment through visible examination ("Dusted", 2006).
First, I have cleaned my fingers and pressed my right-hand fingers on the glass. After that I have immersed the glass in a bowl for 5 hours at room temperature. I took out the glass wearing gloves. I found my finger prints on the glass.
In the second experiment, I performed the same procedure but immersed the glass in hot water and kept it for 5 hours. The hot water was prepared by boiling the tap water. I found my finger prints to be more prominent. The hot water created humidity which made the finger prints more visible.
In the third experiment, I performed with cold water and again kept the glass for 5 hours. The cold water was done by stirring ice cubes. It lowered the temperature of the water. I found that my finger prints were visible and clear.
In the fourth experiment, I did it by adding salt so that I can infer the reactions of chemicals. I have added a tablespoon of common salt. After repeating the same procedure for 5 hours in salty water, I found that my fingerprints were visible. I have not tested it on different amounts of salt.
The last experiment was adding liquid soap in water. I added liquid soap of one tablespoon and repeated the same procedure. After 5 hours, I found that my finger prints were visible but the prints were very light.
Result
So, after the experiment were done I can conclude that the temperature has effect on the finger prints. When the hot water cooled down then the fingerprints were clearly visible. The finger prints were more visible when the water became cool and the visibility increased in cold water. In case of hot water, it is difficult to conclude the result if kept for long hours. Fingerprints react with chemicals like salty and soapy water. Fingerprints are visible in salt water but cannot be seen in soapy water. Common salt is composed of sodium chloride so fingerprints do not react with sodium chloride but react with chemical present in liquid soap.
Conclusion
This one of the elementary fingerprint analysis that is done at home but there are common powders used by investigators to show the latent prints like cyanoacrylate, iodine fuming, silver nitrate, Ninhydrin, DFO, Sudan black, small particle reagent(SPR) (Daluz, n.d.). These are performed on non-porous surfaces. The main aim is to use these methods in crime scenes ("A Simplified Guide To Fingerprint Analysis", 2017).
References
Daluz, H. Fingerprint analysis laboratory workbook (1st ed.).
Dusted. (2006). Retrieved 6 January 2017, from http://www.omsi.edu/sites/all/FTP/files/chemistry/U7Dusted_OpGuide.pdf
A Simplified Guide To Fingerprint Analysis. (2017). Retrieved 6 January 2017, from http://www.forensicsciencesimplified.org/prints/Fingerprints.pdf
