Silicone rubber casting is most effective for preserving which type of fingerprint impressions?

Silicone rubber casting is most effective for preserving plastic fingerprint impressions because these types of impressions are three-dimensional and can capture fine details of the ridge patterns that are integral to fingerprint analysis. Plastic prints are formed when a finger presses against a soft material, such as wax, clay, or some kinds of paint, resulting in a tangible impression that maintains the shape and texture of the ridges.

Using silicone rubber allows for a flexible and detailed capture of these impressions, which can then be analyzed without damage to the original print. This technique also enables the preservation of prints that may not be easily recoverable using other methods, making it a valuable tool in forensic science.

Other types of fingerprints—such as visible prints, which are easily photographed and do not require casting to preserve, and latent prints, which are typically found on non-porous surfaces and generally require powders or chemical methods for development—do not benefit as much from silicone casting. Friction is a descriptor for the kind of ridges found on fingers, not a distinct category of fingerprint impression. Thus, the effectiveness of silicone rubber casting is clearly focused on preserving the intricate details of plastic fingerprints.