How does fingerprint powder work

Questioned Documents. Latent Prints. Careers in Forensic Science. Breath Testing Program. Courtroom Testimony. Crime Scene Processing. Evidence Submission. Common ingredients in black power include graphite, charcoal, lampblack, photocopier toners and anthrocene. Powders may also combine a number of compounds.

Dactyl black is made from a combination of graphite, lampblack and gum acacia. Haddonite black is similar to dactyl black but uses powdered acacia instead of gum acaca. Another black powder is called Dragon's blood; it uses the powdered resin of the Daemonorops draco plant. Additional inorganic materials that are added to fingerprint powders include aluminum dust, fluorescent powders, magnet powders, lycopodium and other metal powders.

Additional items commonly found in fingerprint powder include:. Fingerprint powder is typically gently brushed onto an area, or it is poured onto an area and excess powder is blown away. Magnetic powders use magnetism to keep prints intact; a brush cannot damage any latent prints.

Magnetic Black Powder. Magnetic Black Powder is a granular powder containing pigment, metals and metal oxides. Black Magnetic Fingerprint Powder is typically used on non-porous, light-colored surfaces. White backing cards should be used to provide a sharp contrast.

This type of powder can be used on numerous surfaces including glossy paper, polished wood, leather, plastic, glass and rubber. The powder may be used on plastic surfaces that have been treated previously with superglue fuming. Magnetic Silver Powder. Magnetic Silver Powder is manufactured in much the same way as Magnetic Black Powder except the pigments, metals and metal oxides used in its formulations are of course lighter.

With Magnetic Silver Powder the metal oxides used are finer giving it its silver-like colouring. This powder is generally more effective on rough, grained or porous surfaces whereby a good colour contrast is required. Fluorescent fingerprint powders are used in conjunction with an alternative light source i. It allows the visualisation of latent prints which otherwise may go undetected when using conventional processes.

Suitable for either rough or contaminated surfaces or multi coloured surfaces where it may not be possible to choose a conventional powder which separates the latent print from its background. Easily applied with either a soft brush these powders fluoresces at slightly different wavelengths to provide a choice when dealing with problematic backgrounds.

The transferred outline of the friction ridges is what is known as a latent print. Latent prints are not readily visible to the naked eye. As a result, these "hidden" prints must be "developed" in some way to increase their visibility and contrast. The most common method of developing latent prints on nonporous objects is to physically enhance them by applying fingerprint powder. Fingerprint powder is composed of many different ingredients that can vary greatly depending on the formula used.

Most black fingerprint powders contain rosin, black ferric oxide and lampblack. Many also contain inorganic chemicals such as lead, mercury, cadmium, copper, silicon, titanium and bismuth. Fingerprint powder is applied by brushing it onto the surface and works by mechanically adhering to the oil and moisture components of the latent print.