How Does Superglue Fuming Work?
Superglue fuming is a chemical process to reveal and “fix” latent fingerprints on non-porous items such as bottles, firearms, knives, etc. The process work by heating liquid cyanoacrylate (i.e. superglue) which releases gaseous vapors that adhere to the oily residue of the fingerprint. In the laboratory this is done in a fuming chamber. When I first began my career this amounted to a fish tank. It was simple, crude, and messy. While I suppose some smaller agencies may still use these tanks the vast majority of modern labs use a chamber designed specifically for this function. These chambers control humidity and heat activation. Humidity is an important factor to control because the moisture in the chamber helps to re-hydrate the fingerprint residue. They also evacuate the dangerous fumes so the examiner isn’t exposed to them when they open the chamber up. With the old tanks we’d throw open the lid under a fume hood and run so as not to be exposed to the dangerous vapors.
Examiners can also use a fuming wand to expose items to the cyanoacrylate vapors. They are basically butane fueled lighters that heat small brass capsules of cyanoacrylate infused packing. These wands are typically used in the field on larger items that can not be moved or placed into the fuming chamber. Care must be taken not to inhale the vapors and a safety mask is recommended for use. Also, since the wand can get very hot you don’t want to lay it on anything flammable.
Upon development the fingerprint ridges will appear a white chalky color. In this state they may be photographed, treated with fingerprint powders and lifted, or treated with liquid dye staining reagents and photographed with an alternate light source. The impressions are much more durable than in their untreated state which means an examiner may have an opportunity to make a second or third tape lift if need be. All in all, superglue fuming is one of the most common techniques in the laboratory for processing non-porous items for fingerprints.
Posted on May 22, 2011, in The Crime Laboratory, The Crime Scene and tagged AFIS, automate fingerprint identification system, Crime Scene, csi, Cyanoacrylate fuming, detective, fiction, finger print, fingerprint, forensics, mystery, police, superglue fuming, thriller, tom adair. Bookmark the permalink. 9 Comments.