Obtaining Electronic Impressions

The procedure for obtaining electronic fingerprint images is similar to those for obtaining inked impressions.  The ink, inking plate and fingerprint card are replaced by the glass platen on the live scan fingerprint device.

The person to be printed should stand in front of and at forearms length from the glass platen.  The positions of both the person and the technician should be natural and relaxed if the best fingerprints are to be obtained.  In order to take advantage of the natural movement in making finger impressions, the hand should be rotated from the awkward to the easy position.  This requires that the thumbs be rolled toward and the fingers away from the center of the person's body.  This process relieves strain and leaves the fingers relaxed upon the completion of the rolling so they may be lifted easily from the platen without danger of slipping, which smudges and blurs the prints.

Just as with inked impressions, excessive perspiration will result in the fingerprint images not being clear.  When this situation is encountered, the person's fingers should be individually wiped clean and immediately printed.  This process should be followed with each finger.  It is also possible to wipe the fingers with alcohol or some other drying agent which will temporarily reduce the amount of perspiration and thus permit the technician to obtain clear, legible fingerprint impressions. 

With live scan fingerprint devices, the glass platens must also be kept clean and free of scratches.

In taking the rolled impressions, the side of the bulb of the finger (tip of finger to below first joint) is placed upon the glass platen and the finger is rolled to the other side (fingernail to fingernail) until it faces the opposite direction.

Rolling a finger on a glass platen

To obtain "plain" impressions, all the fingers of the right hand should be pressed simultaneously upon the platen.  The left hand should be similarly printed, and the thumbs of both hands should be pressed on the platen without rolling.  The "plain" or "simultaneous" impressions are used as a check upon the sequence and accuracy of the rolled impressions.

Plain impression on a glass platen