Boston explosives

I’m setting aside the tears that come from looking at the pictures and reading the articles and just channeling “Spock” as best I can on something I know a little bit about.

The first thing I noticed from watching the video and then from the still photo I found at the Los Angles Times is that this looks like a crude homemade bomb.


Here is a cropped version from the Boston Globe YouTube video:


This is a full two seconds later from that same video:


See all that flame? And it looks as if there is still fuel burning in the cloud two seconds after the explosion.

I’m almost certain that no commercial or military explosive produces that much flame. Something like that would be totally banned in the mining industry.

That may mean there was a great excess of fuel in the explosive composition. Boomerite has an excess of oxygen which makes for easier detonation. Maximum power comes from a balance of oxygen and fuel. Some explosives are naturally oxygen or fuel rich. For example TNT is fuel rich. During WW II they would add ammonium nitrate which is (under the proper conditions) an explosive that is oxygen rich. The excess oxygen in the AN increased the power of the detonation by consuming the excess fuel of the TNT.

With that much flame persisting that long after the explosion occurred means huge amounts of power was wasted in light and relatively slowly expanding gases. This was not a military grade explosive. Getting the most bang for the least weight is worth the cost of getting the oxygen balance right.

This means it’s a homemade explosive.

Another possibility is that it wasn’t really a detonation at all but rather a deflagration. For example gun powders typically do not detonate. They “just” burn very rapidly. The flash you see at the muzzle of your gun at night (and sometimes even in bright sunlight) is composed mostly of burning particles of gunpowder. Confine the powder in a strong closed container, such as a pipe, and you get an explosion when the container bursts.

From the sound of the explosion and the speed of the blast product development I’m leaning toward a deflagration.

Mr. Completely sent me an email asking if I could “rule either in or out that readily available reloading powder could have been used”. My answer to that question is that I think it is definitely possible.

Update April 16, 6:20 AM: At least one source says:

…the devices used gunpowder as the explosive and were packed with ball bearings and other shrapnel to maximise injuries.

Update April 16, 1:25 PM: Rick Boatwright has an excellent analysis which points to black powder being the explosive.


40 thoughts on “Boston explosives

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  3. Thanks Joe, this is exactly what I wanted to see when I came here this morning.

    Let’s hope the perpetrator is caught soon.

  4. Looking at the amount of smoke, it might be black powder or a black powder substitute like Triple7 or Pyrodex. That’s just a guess, but I can’t imagine something like Bullseye, Unique, or IMRxxxx making that much smoke.

    • You are right. That is a lot of smoke. But I wouldn’t rule them out yet. “Smokeless” powders aren’t so smokeless under low pressure conditions.

      • “Smokeless” doesnt produce pure white smoke as the device in Boston did. It appeared to be a Low-order detonation (Or deflagration), you can see people in the street directly adjacent to the initial device relatively unaffected by it physically, and reacting quickly to start ripping down the barricades to provide aid to victims at the scene of the detonation. I have the sinking feeling that it’s going to be determined to have used BP, although TATP and other peroxide-based agents can produce white smoke, they are usually much higher-order, higher velocity explosives, unless of course it was improperly mixed. At this point, until and unless we hear anything official it’s all just speculation. Whoever the actor is though, looked like he was definitly going for maximum casualties. From the photos, the devices were near the buildings, focusing the blast front towards the street, and the timing the first smaller device causing people in the area of the second one to stop moving, and look towards the first, creating a larger casualty pool. Somebody put a lot of thought into this, and you have to wonder if it was timed, or command-detonated.

        • From the news reports, I understood the bomb was aimed towards the crowds behind the barriers, not the street.

          • Being within a few blocks of the explosion, I could definitely smell gunpowder in the air after the first one went off. The trash cans involved are all wrought iron/steel construction like the one shown being removed about 0:35 in this video:

            They probably had the added effect of helping to direct the blast upwards as is somewhat evident in the videos of the explosions.

          • I don’t think it was aimed at all. The picture of the burst pressure cooker indicates that the burst direction was random. The blood spray pattern on the sidewalk shows a major stream pointing diagonally across the sidewalk and another about 90 degrees off of that, diagonal across the sidewalk in the other direction. Got really lucky in terms of inflicting casualties. I only saw one of the runners fall.

      • What about TATP?

        That has lots of white smoke and if it was put together by an crazy bastard (or bastards) couldn’t it have a bang + lots of smoke?

        • @Tim – there was no trash can involved at the first bomb. There was a post office mailbox (not the kind that anybody can put mail in – the locked kind that only lettercarriers can access) next to the site. Best candidate for the container that I’ve seen is pointed out here:

          • Wrong. And I immediately retract. Sorry. I had seen a similar clip last night. Today’s clip showed the same cover frame, but goes on to say that many had injuries to the backs of their legs including from pieces of a black nylon bag. Still no indication of a trash can being involved though.

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  6. Right now, based on what I’ve seen/heard/felt from my Re-enacting Days and hanging out with the Cannon Guys, I’m leaning towards Blackpowder myself.

    Which, if true, will probably be put on a Banned List by Obamafiat in a week.

    • Unless I’m reading Joe incorrectly, this would mean that the bomb was not as powerful per weight as it could have been. Our ‘leaders’ would then be forcing bomb makers to resort to using MORE powerful means should they attempt to ban powder.

      I’d prefer to just sit home and live my life, but I have a bad feeling there’s a war coming that I cannot avoid.

      • Don’t you think they would already be using the most powerful things they have to create a bomb? It’s crazy to think they aren’t using the best material they have.

        • No, they used the easiest thing they could get with the least exposure to themselves. If we make it impossible to get BP and pressure cookers, they will start building more dangerous (to build at home) chemical compositions and packing it in things like SCUBA tanks. That will make it more lethal to us, and create more pre- and post- boom exposure to law enforcement for the bombers.

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  8. This is really going to suck if it comes out that it was gun powder, either BP, BP substitute, or some kind of smokeless, especially given the gun debate in the Senate right now. Timing would be almost too coincidental.

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    • While I’ll allow that what they say might be correct, in general I trust the NYT accuracy about as much as Soviet-era Pravda. That is, only if incidental or self-serving for their agenda.

    • Likely not, though perhaps goodby to mail-order supplies. But I think it IS likely you can say hello to a lot more paperwork and ID checks.

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  11. Why hasn’t anyone suggested flash powder? I feel like this was much more powerful than gunpowder would allow. People’s thighs were missing, and it takes a very large caliber bullet traveling at a very high speed to cause that kind of injury OR a very large piece of shrapnel from low order blast. The shrapnel in the bomb was said to be small. I don’t think gunpowder shrapnel has the kinetic injury to cause such devastation… Well I guess if the victims were standing REALLY really close to the bomb, then gunpowder would make sense. I’m thinking flash powder, TATP, or ammonium nitrate with aluminum sensitizer, or smokeless powder since they are the most common. TATP, AN, cheddites could be doused with extra aluminum/fuel and produce a “fake” flame front of the blast which would actually be just extra residual fuel in air suspension that is just riding on air currents of the blast. I’ve seen such an effect on youtube. Check out MOAB video. It would give the ILLUSION of a low order blast. But unless this is gunpowder, it is important to acknowledge that this guy doesn’t understand oxygen balance nor as the other author stated optimal energy transference into shrapnel.

    I’d also like to add, I think this guy PROBABLY put the explosive into a cylinderical shape into the pressure cooker and surrounded it with shrapnel. The cylindrical bomb was probably placed upright and flat on the ground.. In effect, all shrapnel was pushed concentrically parallel to the ground cutting legs and feet and leaving flags etc alone. I doubt the guy meant to do this. In addition, I think most of the shrapnel’s energy was transferred into victims nearby and barricades.. i still think it was a very energetic device stronger than gunpowder… from looking at the injuries.. Anyway, they will probably just do a chemical residue test or look at the shape of the metal fragments and quickly know what it was.

    Okay well now that I think about it, it is very suspicious that there was very little damage to the ground.. no crater/nearby windows ok .. so yeah maybe people very close to a gunpowder bomb. I can’t make up my mind.

    • I thought about it, it is almost certainly flash powder.. lower order explosive but much stronger than black powder. HUGE amounts of white smoke. Could’ve been packed with more aluminum than necessary to create a residual fireball.. very common pyrotechnic material with a big fan base amongst amateur pyros in the USA. Probably a domestic terrorist if thats the case. I dunno why but less foreign terrorists I know ever use flash powder… I guess its just not powerful enough.

      • Black powder is stronger than you think. I have a muzzleloading mortar, and less than an ounce of powder (400 grains) will send a 1 lb projectile (15 oz tin can half-full of cement) over 300 yards.

        Plus, black powder (or a BP substitute) is much easier to acquire large quantities of than something like flash powder: Most gun stores sell Pyrodex and Triple7 (which is significantly more powerful than BP), or BP itself. You can walk in and buy a pound here, pound there, and no single purchase is enough to ring any alarm bells.

    • It is possible that larger pieces of the pressure cooker container caused the more serious injuries rather than the lighter weight fill.

  12. I thought about it, it is almost certainly flash powder.. lower order explosive but much stronger than black powder. HUGE amounts of white smoke. Could’ve been packed with more aluminum than necessary to create a residual fireball.. very common pyrotechnic material with a big fan base amongst amateur pyros in the USA. Probably a domestic terrorist if thats the case. I dunno why but less foreign terrorists I know ever use flash powder… I guess its just not powerful enough.

  13. I read an article a few minutes ago (10 pm central) wherein the attending surgeon said – unequivocally – that there were no “ball bearings”, that the only shrapnel he was finding and removing was that which would be generated by common stuff found at street level.

    • Yeah and sorry for the reposts guys. There was an error and I kept clicking. I hope admin removes cause I can’t. I don’t know who is reporting all this shrapnel stuff (bb etc) if that’s true. Street level stuff being thrown around sounds more consistent with the injuries I saw.

      Don’t get me wrong. I know gunpowder can be REALLY strong if packed right. BUT, a pressure cooker doesn’t have the metallic thickness to warrant such injuries in my opinion(3 mm). I could be wrong, but I’m thinking you need something like a 1 inch thick container with over 15 lbs, but reports are in that the container was only 1.6 gallons, which is not enough space for something like gunpowder to do what was done.

  14. Not flash powder… flash powders contain metal powders like aluminum or magnesium and create a blinding white flash. This was black powder or a substitute. The pressure cooker pieces were relatively large, had this been a higher order “detonating” explosive, the pieces would have been in much smaller fragments. As much as people would like to believe something exotic was used… I believe the evidence points to a very crude, simple device using common black powder.

    • Hi Mike, I think you are absolutely right, no fast flash seen so no flash powder. I’m having trouble believe black powder in such a relatively thin pot can cause that much damage. Either way, I feel was definitely a low order device more strong than gunpowder even if it was something more energetic like armstrongs mix or some other chlorate/ stronger oxidizer composition. I could be wrong.. maybe that pot was extraordinarily thick or that black powder was very fine/rice hulled.

      I have a strong feeling this was domestic. Low order, ricin – right out of the jolly roger cook/amateur guerrilla tactics book. I think this guy was inspired by middle eastern bomb videos probably a liveleak watcher.. but he made ineffective shrapnel spread concentrically parallel to the ground. Every middle eastern terrorist understands there’s a reason you wear it at chest level.

  15. FYI: Wired magazine is running some articles about the explosives, also linking back to David Codrea’s article on the FBI being interested in ease of access to exploding targets, that same report has a link to boomershoot in it… not sure exactly where they are going with that though… boomershoot is run through an FEL and we’ve all had our background checks.

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