Gunpowder issues...

Ren said:

In one of the final scenes in my book I'm asking one of my characters to put gunpowder down a hole, then drop a slightly damp lit rag on top. The theory is that the gunpowder explodes but not immediately. He only needs a couple of seconds before the explosion.

Would that really work? If not what might?

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No being damp won't do it. It will either go off immediately or the "dampness" will wet the powder sufficiently that it won't explode at all.

Instead, rip a narrow strip of cloth say a foot long and sprinkle gunpowder the length of it, fold one side of the narrow edge over the gunpowder trail and twist the cloth tightly. You have just made a fuse. Note that paper, say newspaper, would work better since it burns better and you could twist it more tightly.

Stick one end of the fuse down the hole to the rest of the gunpowder, light the other end and run like hell!

Modern gunpowder is a nitrocellulose propellant designed to burn rather than explode. If poured down a hole, and ignited by your makeshift fuse, it will only burn--and not very spectacularly, as modern gunpowder is also known as "smokeless powder."

If you pour a pound of old black gunpowder down a hole, it will burn much faster (flash) and produce billows of white smoke, but will not explode unless confined, say inside a metal pipe with threaded caps and a pre-bored fuse hole.

Warning! Actual construction of the above pipe bomb is extremely hazardous, as a mere spark from screwing on the final cap may explode it in the maker's face.

Sorry, but mere loose gunpowder can't be counted on to produce the effect you want.

Chase is quite correct, gunpowder of whatever composition, produces several thousand times its volume in gas as it ignites. The gases have to be contained otherwise there is no explosion. So put the fuse down the hole and at least stuff some thick clay into the hole to contain as much of the gas as possible.

For what it's worth, that technique (called mud capping) works at least with dynamite which admitedly is a far more high explosive, high velocity explosive than gunpowder. From my time working as a driller and powder man on road cuts, we used it to shatter large boulders when nobody wanted to perch on top of them with a jack hammer to drill a proper hole for a 1 x 8 stick of dynamite.

One of the downsides of AW is you end up being told far more than you ever intended to know when you ask a question

Mike Martyn said:

One of the downsides of AW is you end up being told far more than you ever intended to know when you ask a question.

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True, but the other side of that is too little info and acknowledgement, as I did.

For instance, your fuse information is vital, and in this case, I only implied the confined aspect of making gunpowder into an explosive agent.

Provided a sufficient amount of gunpowder is available, an eight-pound keg of black powder poured into a small hole of firm soil, properly fused, and mud-capped might produce a sizable "WUMP!"

Off topic: A neighbor farmer I once helped blow out dead cottonwoods when I was a teen put two 40% sticks under roots. The dynamite blast left the tree standing, merely exposing roots like spider legs. Next, he doubled the charge, told me to shovel in mud from the creek, and went to lunch. My mud-cap was a work of art, thickly covering all roots and bottom of the tree. When he touched it off, the tree launched like a Minuteman missle, going at least a dozen feet in the air, before turning on its side and thundering to earth. The blast rattled every window in his house 200 yards away and cracked two. I was thrilled and couldn't wait to launch another tree!

Good story, Chase. I was in my late teens when I worked as a driller and powder man. What is it about teenage males and blowing stuff up?

The biggest one I ever personally let off was for a road cut to accomadate an eight lane highway down through about 90 feet of precambrian granite.

Twenty five thousand pounds of high explosives. loaded through about 400 bore holes. I don't know what the wrath of God might sound like but I've got a fairly good idea!

Mud is wet so if that is used without some way to protect the fuse and the pyrotechnics from the water, it would likely fizzle out.

One summer we were gettting attacked by ground hornets. Most of my family is allergic. This was before the days when people had air conditioning, except for the wealthy, so hiding inside wasn't much of an option. They tried all sorts of sprays without any apparent effect. I made a few apple traps which helped to some degree. Finally I watched them and traced them back to their hole in the ground. It was a particularly dry summer so the ground was dry. I waited until night and started filling it with black powder. I was surprised how much would go down a little hole. It kept draining down like an hourglass. After it seemed to form a stable cone at somewhere between a quarter and a third of a pound, I made a trail and lit it. Visually, it was worthy of the movies with a flash and raining down of dirt but the sound was disappointingly a muffled woof.

pack it anyway preferably with heavy clay and while you.re at it, mound as much clay as you can over the hole. The more of the gas you contain, the bigger.

Waterproof your fuse with grease, tallow, animal fat etc