Depletion series, which is a series of fingermarks deposited consecutively by the same finger from the same donor on a surface, were used in the experiments. Theoretically, fingermark residue will be degraded after each contact. Therefore, the more good quality fingermarks in a depletion series that a powder is able to develop, the more sensitive and better quality the powder is. The above statement is only true if the fingermarks were deposited with a consistent pressure from the same donor.