General Study Guide - Ontario Police College

SUBSTRATES AND SUGGESTED LATENT IMPRESSION ENHANCEMENT
TECHNIQUES
(O.P.C. F.I.O. TRAINING MANUAL)
NOTE: The following list represents the techniques most likely to give satisfactory results. The
number of variables involved in any examination makes it impossible to be specific. Each substrate
or exhibit must be assessed on its own merits and the final selection of technique made by the
technician at the scene. Examination of possible inherent fluorescence is recommended prior to
other enhancement techniques. Consideration should also be given, of course, to creating the best
contrast.
The methods listed here are only to give you suggestions and as a place to start your consideration
of which techniques to apply.
Check with your own unit for advice as to which techniques are in local use.
GLASS
Clean
Metallic powder such as aluminum or copper
Greasy
Granular powder – white is first choice but black and red can be used
Dirty (e.g. mud splashed residential, factory or car windows)
Look for take-away impressions, photograph before development process if possible.
Granular powders will be more effective than metallic.
METAL
Highly Polished; Plated; Brushed finish; Galvanized.
Cyanoacrylate fuming or camphor smoke
PAINTED SURFACES
Hard Enamel (e.g. automobiles and household appliances)
Aluminum or copper metallic powder
Granular powders
Gloss and semi-gloss household paint
Granular powders, especially black
Flat paint
Ninhydrin spray, iodine fuming