AP vs. HMTD - Which is the most sensitive?

[Macgyver]

Maybe some of you read parts of the thread about exploding pellets for air/co2 guns in the improvised weapons section.

This is what got me to wonder about the sensitivity of AP vs. HMTD, since I have always believed AP to be more impact sensitive than HMTD.

But after those experiments, I have found out that at least when it comes to impact sensitivity HMTD is far more sensitive than AP!!!

Four equal pellets were filled with the same amounts, two with AP and two with HMTD.

When fired at metal surfaces, both pellet types explode, but when fired on a somewhat softer surface such as tree or a phonebook, only HMTD is sensitive enough to explode.

But maybe this is because AP is more sensitive to friction than shock?

[xyz]

I think that AP is somewhat more sensitive to flame/sparks but then again I have only made HMTD a few times and I don't have much experince with it.

The reason that people usually say that AP is more sensitive is because AP forms much larger crystals than HMTD. HMTD does not suffer from the sublimation problem either.

[Macgyver]

Originally posted by xyz
I think that AP is somewhat more sensitive to flame/sparks but then again I have only made HMTD a few times and I don't have much experince with it.

The reason that people usually say that AP is more sensitive is because AP forms much larger crystals than HMTD. HMTD does not suffer from the sublimation problem either.

I think you are right on that, HMTD crystals are definitively smaller.

Hmm, think I am going to make a small test right away, since I have both AP & HMTD stored in small amounts.

Result: When approached with a lit match AP ignites much sooner than the HMTD does.

Only thing I haven't compared so far is the friction sensitivity, but I think I remember AP as beoing more sensitive to friction than HMTD if I am not mistaken.

Funny thing is I have always been more afraid of AP than HMTD. But one thing I can say is that HMTD is no problem for long term storage, I have some that is far older than 6 months, still works fine. :D

[jfk]

well i make HTMD 24/7 im a real fan, ive only made AP three times and it less powerfull than AP in the same ammount. i make my AP ofer 2 hours of addition at 0 degrees, im yet to ever set it off with a hammer or friction. however it is easier ot set off than HTMD so must be more sensitive

[xyz]

jfk, AP is difficult to set off with a hammer, it takes a very solid whack and even then it doesn't always go off.

[Macgyver]

Originally posted by xyz
jfk, AP is difficult to set off with a hammer, it takes a very solid whack and even then it doesn't always go off.

I haven't dared to try this yet, but probably a good idea to test AP's friction sensitivity would be to place a small grain between two pieces of sandpaper and rub them against each other.

If you ever try this, use only a small grain of AP and make sure to wear proper protection...

[xyz]

If you do try it, use a tiny amount and wear hearing protection and a face shield.

[0EZ0]

jfk, AP is difficult to set off with a hammer, it takes a very solid whack and even then it doesn't always go off.

xyz, could you provide a little more information on your tests of shock sensitivity?

If anyone has a reference of shock sensitivity of an explosive compound, please include such specifics as what surface you place the test sample on, what you hit it with, how hard you hit it and what kind of reaction you witnessed of the test sample. It helps other people to not misinterpret what you say. Such misinterpretation of information can lead to quite nasty accidents. And if indeed your report shows any misunderstanding of the results, other members can help to clear it up so that you keep all of your fingers intact :D .

I say this because of how you test a sample can indeed effect the results. Try testing the shock sensitivity of AP on a variety of surfaces using a metal hammer of choice. Make sure all test samples come from the same batch of explosive compound. Exercise caution and wear appropriate protective equipment . Surfaces to test should include something like the following. Eg. on a wooden surface (block of wood), on uneven surfaced concrete (pedestrian pavement), on brick paving, on smooth concrete (garage floor) and on a solid metal surface such as an anvil. Record the results and draw your own personal conclusion. The results are destined to vary ;) .

Back to the discussion at hand...

Personally I have never even contemplated making either of the explosive peroxides listed :) . But I would suggest that HMTD would be less subject to flame, shock, and friction sensitivity as AP. AP is more volatile and tends to evapourate quite substantially over time, provided the temperature is stable. Storing AP in a closed container should be avoided, as the AP can evapourate and condense crystals around the lid of the container. The effect is enhanced when stored at a heightened temperature. Just the action of removing the lid and subsequent stress on the crystals can cause the AP to explode. HMTD is also subject to volatilization but much less so than AP and is only really noticed at elevated temperatures.

AP is less reactive in that it does not usually form dangerous compounds on contact with metals or similiar foreign materials. Provided that the sample is relatively pure and free of chemicals from manufacture. HMTD on the other hand is quite reactive and prone to explosive decomposition when it comes into contact with most metals and some other foreign materials. Usually due to heating up of the sample as it reacts with the material it is in contact with.

HMTD mostly displays a heightened sensitivity when in an acidic environment. AP seems not to display such a noticeable rise in sensitivity. But I would still make sure that after manufacture, both compounds are treated to bring the Ph to neutral.

As for crystal size, AP usually forms larger crystals than HMTD. Storing AP over time wet, or damp may cause crystals to amalgamate into a single mass or into larger crystals. Larger crystals = more sensitive to shock and friction, while probably having an enhanced Deflagration to Detonation transition as well. If the crystals are brought back to a smaller size, sensitivity should be reduced substantially. Reducing crystal size by crushing is not advised!
HMTD does not seem to show any rise in crystal size during storage. Although different people may have had different experiences.

When ignited by flame in open air, without external confinement, in small amounts (sub gram), AP deflagrates producing a visible fireball. When amounts larger than approximately 3 grams, the AP can go from Deflagration to Detonation causing an audible bang to be heard and subsequent destruction of the surface it was placed on. HMTD seems only to deflagrate in open air. It is less likely to go from Deflagration to Detonation than AP unless tested in much larger amounts than 3grams.

When heated over a flame, AP melts into a liquid then can visibly form vapour leaving the sample. When heated higher it detonates with all it's intensity, usually destroying or damaging the surface it was heated on. I have no reference as to how HMTD behaves in the same environment. But I suspect it would detonate similarly if heated above a flame.

Both AP and HMTD have little trouble going from Deflagration to Detonation with the aid of confinement. To enhance the speed of detonation, pressing the compounds into a suitable container certainly helps. Again, exercise caution and wear appropriate safety equipment if attempting such things.

If testing, only ever use very small amounts, as in sub gram quatities. Never underestimate the power explosives contain and how little outside manipulation it takes to unleash their fury. I don't condone the clandestine manufacture of explosives. All information written is strictly for theoretical use. Take part in experiments at your own risk.

Please do correct any mistakes I may have made or offer any further comments on the subject.

Hope that answers a few questions :)

[John Ashcroft]

Those who are not able to detonate their acetone peroxide with a hammer blow must either have two twigs extending from their torso, or, unbeknownst to them, have failed to completely dry their product. I've found that acetone peroxide is relatively easy to detonate by smacking with a hammer (relative to detonating sensitive secondaries such as picric acid with a hammer blow, that is).

The sensitivity of acetone peroxide prepared at room temperature is *vastly* greater than the sensitivity of acetone peroxide prepared in temperatures below 0C. It detonates with a light rap of the hammer.

Wet acetone peroxide is considerably less sensitive than its dry counterpart. Usually it'll just splatter when shocked, or merely offer a feeble bang.

[xyz]

xyz, could you provide a little more information on your tests of shock sensitivity?

The AP was on a concrete surface and about 0.1g was used, Only a reasonably small hammer was used though. It usually detonates when struck hard.

There would have been minimal (if any) moisture content in the AP but there could have been some.

Still, I don't advise anyone to go around whacking AP with hammers unless they want a hammer sticking out of their face.