Chemical & Engineering News,
July 24, 1995

Copyright © 1995 by the American Chemical Society.

How one chemist's outrage sparked a counterterrorism invention

At about 3:45 AM on Aug. 24, 1970, a bomb made from ammonium nitrate and fuel oil exploded in Sterling Hall of the University of Wisconsin, Madison, in protest against the Vietnam War. The target, the Army Mathematics Research Center, a Department of Defense project, survived. But Robert E. Fassnacht, a postdoctoral student in the physics department, was killed. Three other people were injured.

Richard G. Livesay, at the time a research chemist with 3M (St. Paul, Minn.), heard of the blast on the radio. "I was furious," he recalls. "This was not a political [statement]. It was murder." The bombing spurred Livesay to consider what could be done to track the perpetrators. On the weekend following the bombing, he recalls, "I asked a simple three-part question: What could be put into explosives that would survive a blast, be recoverable from the debris, and provide some information?"

The answer is Microtaggant, microscopic color-coded plastic particles that can be used to mark explosives. Using his broad knowledge of 3M technology, Livesay went on to invent this product.

The first particles were glass or ceramic beads, similar to microspheres used in marking highway signs. "We thought by introducing extraneous elements at controlled concentrations, we could develop a chemical code" based on the element itself and its amount in the bead, he says. The code then could be read by analyzing the bead with an electron microprobe analyzer.

Customer sample of Microtrace's Microtaggant particles.

Tests showed the codes specified by various elements at very carefully defined levels could be differentiated by the instrument. Further tests showed the beads can survive a blast and can be recovered from debris. "But to read the code, I needed the [electron microprobe analyzer]," says Livesay, "which is neither cheap nor simple."

Another problem was brought up by the explosives industry, Livesay says. He recalls one industry executive saying to him: "Those little microspheres are grit particles. ... We are very fussy about grit particles, because they sensitize nitroglycerine." Testing showed the glass beads indeed sensitized nitroglycerine.

A different material was needed. The 3M researchers tried a plastic-type matrix and got excellent results. It survived blasts. And as more of the plastic taggant was put in, the nitroglycerine became less sensitive to impact and friction. The plastic acted as a dopant.

As it now exists, Microtaggant is the ninth version of a series of attempts to get the perfect particle, says Livesay. He credits a colleague, Edward J. Stevens, formerly a 3M mechanical engineer, and the openness at 3M as critical contributors to the development of his invention. He recalls: "At that time, and even now, 3M allows you to use about 15% of your normal time to work with any darn idea that comes to mind. ... And when I went to people to pick their brains, nobody ever turned me down. It was a fine example of technical cross-pollination."

In 1978, the product was tested nationally, tagging 1% of explosives produced in the U.S. Law enforcement officers were taught how to look for and isolate the particles and how to read the code. The utility of taggants in law enforcement was proven in 1980 when they became critical evidence leading to the conviction of a bomber in Baltimore.

Ironically, the Baltimore case also may have caused explosives manufacturers to lobby against bills requiring taggants, says Livesay. The case showed a criminal act can be traced to a given company's explosives. "The company might be considered liable. That was the scary point," he says. "My view is that the law can be written so that legitimate manufacturers need not be held liable."

Frustrated with the debate over taggants, 3M gave up on this product line and offered it for sale. In 1985, Livesay acquired the license to the Microtaggant patents and formed his own company, Microtrace, in Minneapolis. Now 73, he is still the company's technology director.

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