QC#86 – Thunder Caps

A handful of “impact sensitive” stickers are made from sticky-dots and match heads. They explode when hit with hammers and rocks, then get used as exploding targets, for BB gun practice.
Get the Project PDF and watch the video before it’s even released: http://bit.ly/ThunderCapsPDF

Full tutorial: How To Make Thunder Caps: http://bit.ly/ThunderCaps

Next Video: QC#87 – Rocket Wadding: http://bit.ly/QCRocketWadding
Previous Video: Quick Clips #85 – Drippy Drink Catcher: http://bit.ly/QCDrippyDrinkCatcher

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“Quick Clips” are clips of random experiments in a minute or less.

For other project videos, check out http://www.thekingofrandom.com

Endcard Links:

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Music by Scott & Brendo “One More Time” Instrumental
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Project Inspired By: A moment of inspiration I had while working on the Exploding Cap Dart video (http://bit.ly/ExplodingCapDarts)

WARNING: This project should not be attempted without adult supervision. These improvised caps are loud, and can be dangerous if misused. Safety precautions should be in place to mitigate any chance of personal injury. Be safe and have fun, but always remember that any project you try is at your own risk.

Project History & More Info:

Do you remember the Exploding Cap Dart project? (http://bit.ly/ExplodingCapDarts)

While I was working on different prototypes for that exploding blowgun ammo, I got wondering about the cap-gun caps themselves, and how they exploded on impact.

I spent a considerable amount of time on the internet researching, and trying to figure out what the composition of cap gun caps were. I was very curious to learn what composition could be stable enough to sit undisturbed, indefinitely, but explode suddenly and powerfully when hit with enough force.

I was amazed when I learned it was a pyrotechnic mixture called Armstrong’s Mixture.

Armstrong’s Mixture is highly volatile and extremely dangerous compound in large quantities, and has been known to explode just by stirring it too aggressively. However in small batches like cap-gun caps, it’s exciting, and relatively harmless.

I found a few websites, PDF’s and online studies suggesting different ways to make improvised versions of the mixture using safety matches. This method doesn’t create a pure composition though, and there really isn’t any way to measure exact amounts. But in experimenting, I did figure out an easy way to make it work consistently, every time.

At this point I have a fair amount of experience with Armstrong’s Mixture, and some things you need to know about it are this;

– When making, or handling, Armstrong’s Mixture, treat it like it could explode spontaneously at any moment, and make sure you have safety precautions in place. This way if it does, you’ll be prepared for it.

– It you like your fingers, you need to stick to very small batches, and treat it with caution and respect. Don’t use more than 1 match-head. 2 at the most! This makes enough powder for 10 Thunder Caps, which are about 5-10 times more powerful than regular cap-gun caps in-and-of themselves. And while the powder from only 2 matches might not seem like much … trust me, you DON’T want it going off all at once.

– Armstrong’s Mix can detonate in open air, even if it’s on a flat surface. It doesn’t need to be confined in a container to explode.

– If you mix it up too aggressively, it can go off unexpectedly, and can be extremely loud, leaving your ears ringing. It can also be set off with friction, impact, heat, and electrical sparks. Wear ear-plugs and safety glasses at all times.

Saying all that, I’ve never actually had the composition go off unexpectedly, so long as I was being extremely gentle with it.

I usually keep each movement as light as a feather and typically mix it with wooden sticks, razor blades, and anything else that is convenient and expendable, so far with 100% success. It’s important to note that I always expect it to go off at any time, and am prepared in case it does.

Attempts to get the mixture to go off while stirring aggressively were hit or miss. Most of the time nothing happened. However, every now and again, it would explode when it was least expected.

The purpose of this experiment, for me, was to understand the science behind cap-gun caps and impact sensitive pyrotechnics.



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