Analyzing Fingerprints (Forensics 3)

Today we analyzed the fingerprints that we made yesterday. Our teacher showed us many different techniques that they use in real crime labs.

First Method: Using carbon black or aluminum powderFeatured image  Featured image

1. Open the jar with the carbon black powder and sprinkle it on your already-made fingerprint.

2. Tap the slide with the fingerprint on it lightly so that all the excess powder comes off.

3. Pour the excess powder back into the jar so you don’t waste it.

4. Now you can see your fingerprint more clearly!

Second Method: Using ninhydrin to detect fingerprints (Ninhydrin is a chemical used to detect fingerprints that are just from the oils on our skin.)Featured image

1. Use the oil on your face to print your fingerprint on filter paper.(Obviously you can not see yet)

2. Then, pour a little bit of ninhydrin on the paper and leave it to dry. (takes about 2-3 hours)

3. See your fingerprint slowly turn pink so you could see it more clearly.

Featured image
This is not my fingerprint. (from Internet)

Third Method: Using Iodine Crystals

1. Again, use the oils on your skin to print your finger but put it on normal paper instead.

2. Tape the paper to the inside lid of the jar.

3. Ask an adult to pour in only a couple iodine crystals into this jar and close the lid on rapidly.

4. See what happens to the fingerprint.

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