Techniques and Chemicals used for Developing Fingerprints

There are several techniques to develop fingerprints:

The traditional or most common technique of fingerprinting is taking impressions of a person's hand with the help of ink. Pressing fingers covered in ink, on to a paper is the way of obtaining fingerprints.

                                                      

Rosa Parks being fingerprinted (1955)

For the digital scanning method, a sensitive touch-pad is used to capture the fingerprints of a person or a suspect in this method. The impression of fingerprint recorded on the touch-pad is then compared with thousands of impressions with the help of software or stored in the system.

For the lifting method, oil from hands which are left behind are captured by means of powders made from resinous polymers. To make a distinct fingerprint, dark-colored powders are used on light surfaces and vice versa. In order to put the fingerprints on porous materials, chemicals such as Ninhydrins are used. The super glue chamber is used to place object taken from the site of crime. The glue present in these chambers adhere to the fingerprints and thereby makes them visible.

The laser technique is one of the most useful for capturing fingerprints. In this fingerprinting technology, the fingerprints from many different surfaces can be lifted by using of laser.