Fingerprint powder

In general, two components are present in dry non-magnetic fingerprint powders: a colour, typically inorganic in nature, and a material for adhesion within the powder such as stearic acid, cornstarch or Lycopodium powder, the spores of the Lycopodium and other related plants. A filler material such as mesh pumice is often added to keep the colour and adhesion material together, while preventing the formation of large clumps within the powder that would result in ineffective application onto the surface. Nanopowders Nanopowders are a relatively new type of powder composed of nanoparticles. Similar to magnetic powders, these powders provide greater ridge detail in freshly deposited and aged fingerprints due to the extremely small particle size. Infrared powders Infrared powders are used in conjunction with infrared light. The features of the fingerprint are distinguished from the surrounding background because the infrared light is absorbed in the fingerprint rather than reflected. These powders are most beneficial for enhancing fingerprints found on money bills in countries that use polymer currency, because the powder removes issues related to the visualization of fingerprints on items with colourful, reflective and fluorescent properties. ==Factors influencing fingerprint powder quality==

There are several factors influencing the effectiveness of fingerprint powders. Consistency The powder should not clump together, because the important identifying details within the fingerprint can become destroyed during the application of the powder. ==Powder selection and application==

In the past, powders were selected based on personal choice or outlined standard procedures of the associated department or agency. Despite this freedom in the powder selection process, crime scene investigators should ultimately choose powders that provide the best contrast against the surface the fingerprints are deposited on, with consideration for the characteristics of the surface itself. Most fingerprint powders are applied with a fingerprint brush composed of extremely fine fibers, designed to pick up powder and gently deposit it through a twirling motion onto the fingerprint, to reveal it without removing the delicate residue composing the fingerprint itself. There are many different types of brushes that can be used for applying fingerprint powder. The choice mostly depends on the stage of fingerprint development. For example, feather fingerprint brushes enhance detail within fingerprints located during an initial search, with fingerprint brushes composed of fiberglass fibers. Fingerprint powder may be applied using aerosol methods that do not involve direct contact with the surface. Magnetic powders differ slightly from traditional powders in the way that they are applied to fingerprints. A magnetic applicator is used in place of a fingerprint brush composed of fibers. The magnet within the applicator attracts the magnetic powder, forming a cluster of powder that can be gently moved across the fingerprint. Once complete, the magnet within the applicator is retracted and the magnetic powder falls off. The benefit to this application method is that no bristles touch the surface, with less potential damage to the print compared to other methods of developing fingerprints. Regardless of the method chosen to apply fingerprint powder, there must be careful consideration not to apply too much powder, which could ruin the fine details within the fingerprint needed to make an identification. In addition, fingerprints contain DNA that can be used in subsequent forensic DNA analysis and, therefore, it is important to mitigate the risks of DNA contamination when applying fingerprint powder. == Further applications/uses ==

Fingerprint powder is useful for the detection and collection of latent fingerprints, but that is not all the analysis that can be done. Kaplan-Sandquist, LeBeau, and Miller conducted a study where they tested fingerprint development methods with the MALDI/TOF MS. The fingerprint powder was found to be useful as a MALDI matrix. This instrument can identify many compounds. In the study, fingerprints tested contained known solvent residues. The fingerprint powder along with the MALDI matrix had the highest average detection rates of (88%). Since this study was controlled, it is known that the use of this further application with the MALDI/TOF MS would be effective. == Associated health concerns ==

Fingerprint powders used in the past contained materials that were considered carcinogenic and toxic. Lead and mercury components were removed from fingerprint powders due to associated cases of mercury and lead poisoning. Modern fingerprint powders pose significantly fewer health risks because they are composed mainly of organic components. However, there is concern that the small particles within the fingerprint powders may be inhaled and after prolonged exposure can result in the development of lung diseases. Powders with smaller particle sizes such as fluorescent powders, or the newer nanopowders are particularly concerning because they are small enough to reach and settle deep within the lungs. It is recommended that individuals frequently using these powders take the necessary precautions to mitigate the risk of respiratory illness, whether that be working within a fume hood or wearing a mask. ==See also==