What is it about?
Fingerprints can be developed with many methods, the choice of which may depend on the surface the mark is on, the length of time it has been deposited and if it has been indoors or exposed to the weather. One option is a 'powder suspension': powders in a mix of solvent or detergent, which are painted onto the surface and the excess rinsed off, revealing the fingerprint. This paper examines the effect of particle size and detergent type on a range of surfaces such as carrier bags, ceramic tiles and painted metal. It shows 'tween 20' can be used as viable detergent and particle size is best around or below 1 micrometre (1 micron, 1/1000 millimetre).
Why is it important?
Current formulations are suffering from two problems. The Home Office guidelines are based on a particular batch of powder, which is no longer available; this paper sets out guidance for selection of efficient powders form alternative suppliers. Secondly the formulation of the solution in which the powder is suspended contains chemicals which may affect the environment, this paper highlights replacement formulations which are more environmentally friendly.
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This page is a summary of: Fingermark visualisation with iron oxide powder suspension: the variable effectiveness of iron (II/III) oxide powders, and Tween® 20 as an alternative to Triton™ X-100, Forensic Science International, September 2018, Elsevier, DOI: 10.1016/j.forsciint.2018.09.012.
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