[southernplaces7]

Every so often in HN comments, one finds pearls like this anecdote. Outside the bubble of usually sterile tech narratives and uniquely, hilariously fascinating. Thanks for that... "dyna-wipe".. made me laugh right out loud.

Also, wouldn't the nitroglycerin that sweated out as you describe have constantly been in danger of spontaneously exploding, even in small quantities?

[doodlebugging]

Thanks for reading. I'm glad you enjoyed it. We have a large group of people with such diverse life and career experiences that I think it adds value to give some real-life color to some of these discussions and the parent comment immediately reminded me of my own experiences.

To answer your question about volatility of the nitroglycerin I'll lean on the safety information that we were given back in the day. We were told that there was minimal danger of explosion from the sweating sticks or the materials that absorbed the nitroglycerin because it required significant energy to initiate an explosion. That energy was to be supplied by the blasting caps. They said we could burn the sticks like firewood without risk of explosion since the nitroglycerin was in a nitro-soaked sawdust matrix wrapped in durable paper. They warned against jumping on the burning sticks or throwing things on the fire if you were trying to build or extinguish the fire though since they might be unstable.

Safe handling meant that we were to keep blasting caps separate from "powder" sticks. In normal road transport that was easy since each had separate locked magazines. Once you're in the field, as in this case, you just carried both together and followed normal safety guidelines to minimize the possibility of an accidental detonation of the primer cap. That meant that you minimized impact on the backpack and the copper jackets of the caps and insured that all the cap wires were twisted (shorted) so stray static electricity wouldn't be an issue. The caps all had a two-wire conductor to the primer which needed to be twisted (shunted or shorted) to protect from stray voltages that could cause the cap to fire. They told us that the cap could fire with less than 0.5V and that in the right atmospheric conditions normal static electricity could pop one so it was critical to make sure all were twisted. Normal procedure was to leave them twisted until you were preparing to fire the charge and then you would connect them to the blaster which supplied the voltage to pop the cap.

The blasting caps had approximately the same energy as a .30 caliber bullet impact so in theory you could shoot a stick of dynamite and cause it to explode.

It's been 40+ years since I worked out there and I still wouldn't trade the experience for anything else. It was foundational experience in field operations that set me up for a long career as a geophysicist.

[southernplaces7]

>We were told that there was minimal danger of explosion from the sweating sticks or the materials that absorbed the nitroglycerin because it required significant energy to initiate an explosion.

Thanks for the detailed reply! And sorry I just answered back now. I hadn't noticed it earlier. As for the above. I assumed that the sticks would be pretty stable unless detonated with something like a blasting cap, but I was referring to the liquid nitroglycerin leaking, or sweating out of them. Do you remember if that liquid was pure nitroglycerin or still diluted enough not to be in danger of just exploding suddenly?

[doodlebugging]

You're welcome.

From what I remember the nitroglycerin was held in a fine sawdust matrix and it would sweat thru the heavy paper on the sticks. Since there was dynawipe in the boxes you likely never had beads of nitro form on the outside of the sticks. When carried in a backpack they would sweat into the pack fabric and then straight into your bloodstream.

I suspect that it would be pure nitroglycerin because I heard from friends that after cutting a stick you could scrape small balls of the goo from your brass powder knife and whack them hard with a ball-peen hammer and they would pop.

We used those small paper-wrapped sticks when we drilled mini-hole programs where the shot-holes were 5' (1.5m) deep or less and could be drilled by one man or a two man crew using jackhammers or Little Beaver type augers depending on near surface conditions. For traditional shot-holes that were 80-100' deep (24.4-30.5m) or more we used 5# (2.27 kg) sticks of dynagel (seismogel?) which was a gelled nitroglycerin that could stand long periods of immersion without degrading. These sticks were plastic tubes that could be screwed together to make a charge of any size and the loader could place sets of empty tubes to space charges inside the shot-hole allowing multiple shots to be taken from a single shot-hole. The blasting caps would be inserted at the top of each charge and the loader would label them from deepest to shallowest so that the shooter, who might not get around for a month or more, could fire them from deepest to shallowest allowing the data from each shot in that shot-hole to be stacked for signal-to-noise improvement.