Marking of Plastic Explosives
different from the others, not an explosive
and with no track record as an explosive
additive prior to the requirements.
As aforementioned, many explosives
already used some of the tagging agents
as additives prior to the convention coming
into force and where they were using them
at, or above, the required ratios, the
explosives produced would automatically
be considered to be tagged.
Some states could foresee problems and
built safeguards into the legislation,
allowing small quantities of untagged
materials to be kept, for training and
research purposes.
Overtaken by Events
By the time we had begun to operate what
we now know as Explosive Detection
Systems, integrated into baggage handling
systems, it had become clear that trace
detection would play little more than a
minor role in some countries, and none at
all in others, in screening.
C4 In the meantime states were
implementing appropriate legislation
The widely acknowledged problem with additive in explosive products for a long relating to “plastic” explosives. In most
the more modern plastic explosives, is their time. It is associated with many cases the definition of plastic explosives
low vapour pressures (the amount of nitroglycerine (NG) based explosives, as it mainly incorporated materials based on
material given off into the atmosphere as is added to stop the NG freezing, which it RDX, HMX and PETN, three pretty
small particles). This is why the early would do at around 13° otherwise. So nondescript white crystalline substances
vapour detectors struggled; not that vapour some NG based explosives were actually with very low vapour pressures. In their
detection wasn’t a sound concept, it was “tagged” long before the requirements for powder form, they are not plastic
just that the necessary sensitivity had not “taggants” came into force. Yet, it never explosives. So, if you take for example the
been achieved. really mattered as NG has a comparatively PETN used as the main charge in the shoe
high vapour pressure anyway. IED worn by Richard Reid, it would not have
The Taggants Then there is DMNB, being a little been covered by marking regulations.
The four agreed taggants were:
circle6 ortho-Mononitrotoluene at 0.5% by mass
circle6 para-Mononitrotoluene at 0.5% by mass
circle6 Ethyleneglycol-dinitrate at 0.2% by mass
circle6 Dimethyldinitrobutane (DMNB) at 0.1%
by mass
The MNTs (ortho-Mononitrotoluene and
para-Mononitrotoluene) are derived from
TNT production and are often used as an
additive to other explosives. MNT is well
known as the chemical which gives some
of the Nitroglycernine (glyceroltrinitrate)
based explosives their distinctive almond
like smell. This then becomes a
characteristic of some plastics tagged with
MNT. Freshly manufactured Chinese C4 for
example, has a quite powerful and not
unpleasant almond-like aroma.
Ethyleneglycol-dinitrate is essentially
nitrated anti-freeze and whilst it has a
comparatively high vapour pressure, it
lacks a distinctive smell humans would
remember. It is a high explosive in its own
right and, like MNT, it has been used as an Semtex 10SE
Aviationsecurityinternational April 2008 www.asi-mag.com 15
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