To obtain "plain" impressions of fingerprints, how should the fingers be pressed on the inking plate?

To obtain "plain" impressions of fingerprints, pressing the fingers simultaneously on the inking plate is essential because it ensures that the entire area of the fingertip makes contact with the surface at the same time. This technique allows for a complete and even impression of the fingerprint pattern without smudging or distortion, which can occur if the fingers are pressed individually or one at a time.

Simultaneous printing helps achieve a clear and consistent result, crucial for identification purposes in law enforcement and criminal investigations. If fingers are pressed down individually or one at a time, it can lead to incomplete prints or variations in pressure that may obscure important detail, resulting in unusable fingerprints. Additionally, applying excessive pressure might distort the fingerprint ridges, leading to inaccuracies. Thus, the technique of pressing fingers simultaneously ensures quality and clarity of the plain impressions captured.