Super Cyanoacrylate Esters

The cyanoacrylate ester fuming method of revealing fingerprints was discovered by the Criminal Identification Division of the Japanese National Police Agency in 1978. It was soon practiced all over the world. Amazingly, fingerprint residue exposed to cyanoacrylate ester fumes for brief periods of time become harden tan-colored fingerprint impressions. There are three different esters that are popularly marketed: methyl, ethyl, and n-butyl cyanoacrylate. Superglue itself was first described by Dr. Harry Coover on 1942 while working for Kodak Research Laboratories to develop a clear plastic for gunsights. Coover finally realized that cyanoacrylate was a useful adhesive in 1958 while he was working for Eastman Kodak. It is tempting to conjecture that superglue attaches itself to the surface of the fingerprint residue with its well-known gluing mechanism. However, an article in the Journal of Forensic Science entitled “A mechanistic model for the superglue fuming of latent fingerprints” suggests that clumps of superglue are absorbed into the oily fingerprint residue. This interesting article was written as a result of an undergraduate research project in which the authors describe a series of experiments to determine the affinity of superglue fumes for various substances. Long chain fatty acids absorb the cyanoacrylate fumes very well. In fact, the longer the hydrocarbon chain the faster the deposition of the superglue. A subsequent article in the same journal entitled “Understanding the chemistry of the development of latent fingerprints by superglue fuming” measured the chain growth of cyanoacrylate polymers initiated by lactate. The increase in mass of 45 microL blobs of solution was measured over time. As you might imagine increasing the pH increased the accumulation of superglue mass. These two articles carefully present competing theories to explain the chemistry of superglue fuming of latent fingerprints.

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