Water Experiment

CJ 328-01: Forensic Fingerprint Analysis

Unit 7 Assignment 2

Purdue University Global

Unit 7 Assignment 2

For this assignment we are to take a drinking glass and handle it to make sure that there are fingerprint impressions on it. Then we are to put the glass into water for several hours. Then we are to visually examine the glass to determine if we can still visualize the prints. Then we are to try this in both hot and cold water, soapy or saltwater. We are to keep notes of the results following each situation. Then we are to hypothesize reasons for both similar and dissimilar results with the different conditions.

I located a glass and I did three sets of prints. For the first set I placed the glass into a sink filled with cold but soapy water, then I used just plain hot water, then for the last set I filled the sink with water and allowed for it to come to room temperature. With all three experiments I placed the glass into the water and let it soak for eight hours. For the cold soapy water, the prints were gone when I removed it from the water. There was one partial print on the rim, but that could have been when I lifted the glass to remove it from the water, but that was the only print on it.

When I first took the glass to put it in the sink filled with hot water there were some prints on it that appeared to have possibly oil or grease on them, but I had just put lotion on my hands about 45-minuets prior to picking the glass up to put it in the water. When I removed the glass from the hot water with no soap in it there were partial prints on it that I could make out.

The glass that I placed in the water that was at room temperature still had all of my prints on it when I removed it just as it did when I put it in the water. I observed the prints both before and after placing the glass in the water. This was a good experiment to do, and I was really thinking that there would be prints on the glass in all three conditions of the water.

After ending this experiment, I hypothesized that whatever chemicals are in the soap is why the prints were gone from the glass that I placed in the cold soapy water. Other than the soap the only other differences were with the other water was that one was hot and was in water that was at room temperature. I used a different glass for each of the types of water that I used. The glass that was in the hot water appeared to have lost some of the detail, but this could have been from the heat of the water or the grease or oil from the lotion that I had applied to my hands. There was really not difference in the glass that I put in the water that was at room temperature it appeared to be the same as it was when I put it in there. I do not believe that the chlorine in the water affected the prints at all.

Hot Water