Which surfaces are generally best for developing prints with powder?

The best surfaces for developing fingerprints with powder are non-porous surfaces. Non-porous materials, such as glass, metal, or plastic, do not absorb moisture and oil from the skin, which makes it easier for the powder to adhere to the fingerprint residue left behind. When powder is applied to a non-porous surface, it binds to the oil and sweat present in the fingerprint, allowing for clear visibility of the print when subsequently lifted with tape.

Porous surfaces, on the other hand, such as paper or cardboard, can absorb the moisture and oils, making it more difficult for the powder to adhere properly. This can result in less defined or even lost prints. Rough surfaces tend to create inconsistencies in print development, as the texture can disrupt the powder's ability to reveal clear patterns. Soft surfaces, like fabrics, pose similar challenges as they do not retain fingerprint residues in a way that permits effective powder application.

In summary, non-porous surfaces are ideal for using powder to develop fingerprints due to their ability to retain and display prints clearly, while the other surface types either absorb the residues or create obstacles for the development process.