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A Guide on Explosives Detection Dog Training: What Odors to Train and Why || Precision Explosives
- Yana Allport
- Aug 12
- 10 min read
Hi friends!
Last couple articles you guys got to read all about jars and storage - thrilling stuff, right? Let’s shake things up a bit and talk about what a lot of you have really been asking about:
Now which odors should an explosives detection dog be trained on, in what order, and does the order really matter? (Hint: it does)
The kind of device a dog might find depends a lot on who built it and where. In the US, though, the overwhelming majority of what turns up is pipe bombs and pressure cookers. That fact alone should shape everything about how we train. You are rarely going to be working a big, room-filling odor that the handler can smell. Far more often than not you are hoping for a trace of residue on the outside of a device - the little that transferred to a hand, a seam, a surface. So, like I covered in our article on Training Dogs to Find Small Amounts of Odor, the whole job of explosives detection K9 training comes down to one thing: teaching your dog the ability to work the lowest odor thresholds possible.
What Explosive Odors to Train Your Detection Dog On
Here's PE's recommended order for introducing explosive odors during imprinting, top to bottom.
RDX
RDX is the workhorse of military and commercial high explosives, and the base odor inside Composition A5 and C4. Train RDX well and you've covered a whole family of odors a detection dog might encounter, because the dog was never smelling "C4" as its own thing - it was smelling the RDX inside it. Maybe the C4 was the RDX we made along the way.
RDX is also one of the faintest odors in the entire kit, which is exactly why it leads; build the dog's ability to work a low-odor target from day one!
PETN
Pentaerythritol tetranitrate (PETN) is also one of the faintest odors on this list - as well as the base of detonating cord, blasting caps, and Semtex. If a dog can find RDX and PETN, your dog is well-programmed to find the hardest stuff out there.
TNT
Trinitrotoluene is a great lesson in how an odor picture is never just one single thing. What your dog actually smells coming off TNT is really three components working together: TNT itself, plus 2,4-Dinitrotoluene (2,4-DNT) and 2,6-DNT. Here's the catch - the DNTs have a much higher vapor pressure than TNT, so they dominate the headspace early and burn off faster. That means the scent picture of any given piece of TNT slowly drifts toward pure TNT over time, as the DNT depletes out of it. The DNT is that One Dude who won't let anyone else talk during the meeting.
So run your dog on as much different TNT as you can get your hands on. And when you get a fresh batch in, hang onto the old stuff - fresh and aged TNT genuinely smell different to a dog. Exposing your dog to that full spectrum is what helps it generalize and hold up in the field, instead of locking onto one narrow version of the odor.
This isn't just theory, either. NIST researchers confirmed the whole dynamic using polydimethylsiloxane (PDMS) training aids - they showed that trained detection dogs respond to DNT-infused aids as if they were the real thing, which makes DNT the functionally dominant odor marker in fresh TNT.
Nitroglycerin
Nitroglycerin (NG) is a liquid nitroorganic explosive with one of the higher vapor pressures in the entire explosive catalog - you'll find it sitting up in the upper-middle range of our vapor pressure infographic, well above the nitramines. What that higher vapor pressure means in practice is there's significantly more odor available at the nose than you get off RDX or PETN. That's a big part of why dynamite is so much more detectable.
NG is also the dominant odor marker in double-base smokeless powders - which you'll see come up again a few entries down. Keep that in the back of your mind, because it pays off: imprint your dog well on nitroglycerin now, and that foundation carries straight over!
Ammonium Nitrate
Ammonium nitrate is the oxidizer behind emulsions and a huge share of the world's commercial blasting products - and plenty of improvised mixes too, including ANFO (ammonium nitrate fuel oil), the material used in the 1995 Oklahoma City bombing.
Here's where ammonium nitrate gets interesting for us: it doesn't have a conventional vapor pressure the way nitroglycerin or TNT does. So what's your dog actually detecting? Not ammonium nitrate vapor itself, but a combination of its decomposition products and associated volatiles. Specifically, ammonium nitrate breaks down under normal ambient conditions to release ammonia and nitric acid - and researchers have built dedicated analytical methods around measuring that ammonia signature.
Potassium Nitrate
Potassium nitrate is the "saltpeter" in black powder - the oxidizer in the classic black powder formula that still shows up routinely in pipe bombs. And like ammonium nitrate, potassium nitrate is an ionic salt with essentially no conventional vapor pressure of its own. So what your dog is detecting isn't KNO₃ vapor - it's the volatiles and reaction products released by the mixture as a whole.
Potassium Chlorate
Potassium chlorate is the oxidizer in a whole lot of fuel-oxidizer improvised mixtures. Like the nitrate salts, it has effectively no vapor pressure at ambient temperature - you don't get meaningful vapor off it until you're up around 300°C. And yet dogs find it reliably. That's been an open question in our field for years: how is the dog even doing this?
Two lines of evidence have started to crack it.
First, chlorine. Researchers built an on-fiber SPME derivatization method specifically for this puzzle. Conventional GC/MS can't "see" chlorine, so they reacted the headspace with propylene oxide to convert it into chloro-2-propanol, which the instrument can see. That confirmed chlorine coming off laboratory-grade, industrial-grade, and clandestinely produced potassium chlorate - and notably not off related chlorinated salts or blanks.
Second, particles! A study measuring headspace particulates found nanometer- to micrometer-sized particles lifting off bulk - and even microgram - quantities of oxidizer. These are small enough to travel through the air and deposit right in the olfactory region of the nasal cavity. Aerosol mass spectrometry confirmed those particles were carrying potassium, chlorine, hypochlorite, and chlorite. So your dog may not be smelling oxidizer vapor at all - it may be catching actual airborne particles of the material.
Once upon a time, Lazarowski and Dorman trained Labrador Retrievers on chemically pure potassium chlorate, validated them on it, then tested them against four realistic chlorate-based fuel-oxidizer mixtures. Detection rates came in at 27%, 40%, 38%, and 69%. 87% of the dogs failed to alert on at least one of the four, and only six of sixteen hit 75%. Training a dog on a pure oxidizer salt does not reliably produce a dog that finds real oxidizer devices. Imprint on the oxidizer, then proof on realistic mixtures.
Smokeless Powders
Smokeless powder comes in two main types. Single-base is built on nitrocellulose; double-base adds nitroglycerin into the formula. Double-base is especially important for detection K9 training because its dominant volatile odor is nitroglycerin. Single-base powders are a different animal, producing their own complex headspace of nitrocellulose decomposition products and stabilizers.
Both types matter because both are easy to get. They're sold commercially at sporting goods stores and gun shops all over the country, which makes them one of the most available energetic materials out there for improvised devices. One thing to keep in mind though: dogs detect smokeless powder most reliably under standard temperature and humidity. Performance drops off under high heat and high humidity - and it drops more here than with any other energetic we've tested. So if you're training in tough conditions, factor that in.
TATP
Triacetone triperoxide (TATP) is a homemade explosive synthesized from cheap, commercially available components. Odor-wise, it's one of the loudest targets on this whole list - at 25°C, TATP has a vapor pressure of roughly 6.4 Pa.
On top of that, TATP sublimates: it goes straight from solid to vapor without ever passing through a liquid phase, which means it's continuously shedding odor molecules into the air. That combination - high vapor pressure plus constant sublimation - makes it one of the more detectable explosives out there. It also makes it genuinely dangerous to handle, because TATP is extremely sensitive to heat, friction, and shock. It's the explosive behind the July 7, 2005 London bombings, the November 2015 Paris attacks, and the March 2016 Brussels attacks - and our canine detection teams are a primary line of defense against it.
And that's exactly why real-odor training aids matter so much here. Because TATP is so dangerous to synthesize and store, high-quality training aids aren't a matter of convenience - they're a matter of your team's safety.
HMTD
Hexamethylene triperoxide diamine (HMTD) closes out the list - and it's the perfect one to end on, because it flips an assumption a lot of handlers make. HMTD and TATP are both peroxide-based homemade explosives, so you'd expect them to smell about the same to a dog, right? Not even close. TATP sits at 6.4 Pa; HMTD comes in around 3.9 × 10⁻² Pa - which makes TATP roughly 150 times more volatile.
So don't let the word "peroxide" fool you into thinking "loud odor." HMTD is a much quieter. It actually lives down in the same range as nitroglycerin, nowhere near TATP.
Every odor in this sequence is available as a real-odor Explosives Odor Print, so you would be able to imprint your dog on the actual compounds - all without licensing, handling, or storing live explosives!
Vapor Pressure in Explosives Detection
By now you've seen vapor pressure come up in nearly every entry - so let's pull it all together, because it's the single thing governing what your dog is actually smelling at every step of this list.
Vapor pressure is just how readily a material sheds molecules into the air above it at a given temperature. High vapor pressure means the material is throwing odor into the air freely - a loud target, with plenty of stinky molecules for the nose to grab. Low vapor pressure is stingy; it barely lets anything go, so the odor is quiet. This is what makes something like TNT tricky: in fresh TNT, the DNT is yelling so loudly that your dog can't hear TNT's whisper underneath it.
And the range here is genuinely enormous. A 2025 review in Trends in Analytical Chemistry compiled the best measured vapor pressures for dozens of explosives, and the compounds span roughly twenty orders of magnitude from top to bottom. Even inside our own odor line the spread is millions-fold: TATP at the top puts something like three million times more odor into the air than PETN at the bottom - at the exact same temperature.
Vapor Pressures of Explosives and Drugs, Ewing, Denis & Schrader, Trends in Analytical Chemistry (2025)
The two we start on - RDX and PETN - are the faintest on the whole list. Real devices leak only tiny amounts of odor, so we deliberately build the dog on the lowest-threshold targets first, which also happen to be some of the most operationally important. You can go ahead and blame vapor pressure for making these two the hardest!
How Vapor Pressure Affects Training
But vapor pressure isn't all bad - you can actually use it as a tool when a green dog is struggling during imprinting. If your dog isn't connecting the odor to the reward, won't commit to source, or just looks flat-out confused, try stepping over to a higher-vapor-pressure odor like TATP to help teach the game. Those easy wins show the dog how to work the area, find the source, commit, and get paid - and once that clicks, you can dial the difficulty back up.
Here's what the fix is not, though: making a quiet odor louder. I love the way Sci K9 puts this - "the odorant indole is one of the most common ingredients in the fragrance industry for its pleasant smell, because at low concentrations it smells like flowers. At high concentrations? It smells like feces." If your dog is imprinted on poop, it isn't looking for flowers. You'd have to re-imprint it to find the lower concentrations. So imprint your dog on realistic odor, then train and proof on bulk and trace amounts so it gets the whole picture.
And one last thing, handler to handler: give your dog the time it needs to rub those brain cells together. We're all quick to assume our dog "doesn't get it" - when really, it's just a dog working through a brand-new problem at its own pace. Have patience to allow the learning to actually happen - and then making it rain the moment your dog succeeds!
What Odors NOT to Train Your Detection K9 On
Knowing what to skip is just as useful as knowing what to train - it saves you from burning reps building out a library your dog is never going to use.
Sodium chlorate - Skip it. It isn't used in fireworks and hasn't turned up in a device, so it doesn't earn a spot in your dog's odor library.
Water gel - Also off the list, for a simpler reason: it's essentially not produced anymore.
Explosives precursors - Hexamine, acetone, urea prills, aluminum powder, and the like. These are raw ingredients that get consumed making certain explosives, and it's tempting to figure that training on the ingredients gets you partway to the finished product. It doesn't. A chemical reaction has to happen to turn precursors into an explosive, and that reaction permanently changes the molecules involved. The finished explosive no more smells like its precursors than a cake smells like raw eggs and flour - and you can't un-bake a cake to get them back. Train the target, not the pantry!
Benefits of Precision Explosives Odor Prints
Just about every training problem these articles keep circling back to - imprinting your dog on real explosives odor, holding a consistent odor picture session to session so that imprinting actually sticks, and doing all of it without the liability, storage headaches, and licensing that come with live explosives - comes down to the exact problems Odor Prints were built to solve.
Each Odor Print is made using POCR (Polymer Odor Capture and Release) material infused with real odor. That means your dog imprints on the true target compound - not a pseudo-scent, not a substitute - with none of the actual explosive present in the training aid. They're produced in a controlled environment to keep contamination from other target odors down, they hold a stable odor picture session after session, and they last about a year of regular training.
That combination - real odor, consistent picture, no live explosives - is what lets you set your team up for success without a magazine or a license.
Trust the science, and trust your dog.
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