Techniques and Chemicals used to Develop Prints on Multiple Surfaces Part Two

In recovering latent impressions there are numerous products available for the task. The techniques can be broken down into four simple areas. The conventional methods consist of mechanical and chemical development. The more modern techniques applied today in recovering latent impressions are florescent die stains or powders (aided with some type laser or light source), and superglue fuming. It should be noted that latent impressions on some surfaces may be fragile.

Mechanical Development

Mechanical development is the use of a brush and powder to physically dust the surface. This technique allows the particles of the powder to adhere to the contaminates which causes the ridge deposits. The mechanical development is for nonporous items and surfaces.
There are three types of brushes manufactured for the use of mechanical ridge detail development:
1. Fiberglass
2. Camel hair
3. Feather brush
There are an assortment of powders, lifters and tapes that are specially formulated and manufactured for the use of impression recovery.

Chemical

For protection and safety reasons these methods are applied in the laboratory under well ventilated conditions. A variety of chemicals are produced to react to certain components that make up the ridge deposits. More than a general knowledge of the chemicals as well as the contaminates in the deposits are needed to perform these tasks. The chemical processing techniques are for porous, absorbent items such as paper, untreated wood, and matte, semi-porous finished items.

Superglue Fuming

Cyanoacrylate ester is the active ingredient in superglue. It creates a vapor that polymerizes (creates a white residue) on contaminates such as latent impression deposits. S
uperglue is sold in a liquid or pouch form and comes in a variety of viscosity's. As documented by the US Army Crime Lab, superglue fumes are strongly irritating to the eyes and respiratory system. Personal Safety and caution are the
 keys to this development technique. The primary purpose of superglue in the field is to fix the impression on items where the latent impression may be fragile, so that it is less destructible during processing or transport. It does not make

 the impression indestructible. Without the proper caution the impression can still be wiped away or destroyed.

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