I recently spent a lot of time researching squib designs for a short film that I am working on. I found that most designs were unreliable, unworkable or expensive. I did find several designs that mine ended up being a variation of which use model rocket igniters. But for my purposes, which involve a lot of squibs, this would be too expensive. I decided to find out how to make my own igniters and came across this great site to which I owe a great debt of gratitude to. Using their recipe for igniter goop and the inside of an old hairdryer, I was able to make igniters tat cost almost nothing.
Please note that I am not a professional anything, let alone a pyrotechnican and I take no responsibility for anything that happens from you trying to do what I have done. This is a very dangerous project if not done properly and all possible safety precautions should be taken when attempting it.
That being said...
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Step 1: Materials and Tools
The basic materials for this project are as follows:
For electronically ignited firecracker
1. Nichrome wire (from hairdryer)
2. Black powder
4. Ping pong balls
5. Black cat or similar firecracker
For blood pack:
1. Fake blood
2. Condom (unlubricated for god's sake!)
4. Duct tape
For Battery pack:
1. 3 9v battery clips (sorry, I only had two for the pic)
2. alligator clips
3. Insulated wire
You will also need, along with general tools, a rock tumbler and a bunch of lead balls about 1 inch in diameter to grind down the black powder. These are probably the biggest expense. I happened to have them around so it worked out for me. You could use a mortar and pestle but I personally would not feel safe doing that. It only takes one spark to set off black powder.
If you can find another, safe alternative, please post.
Step 2: Igniter Goop
For the squib to work you need to create the igniter to be able to detonate a firecracker eclectically. This can be done by sticking a model rocket igniter in a black cat but as I said before, at about a dollar each, these igniters can be pricry if you need a lot of squibs. I decided to try to find out how to make these igniters myself and I found this site which gives great info on electronic fireworks detonation. I modified their design to fit a squib.
The first step is to grind down the black powder. This is probably the most dangerous part of the project and great care should be taken when doing this. First take a rock polisher and plug it into a very long extension cord. Take it as far away from anything that you do not want to have blown up. At this point, make sure that the extension cord is NOT PLUGED IN to the wall. Put about two cups of black powder in the polisher and about two cups of the lead balls. Make sure to use lead balls because they will not produce sparks. Once you have the polisher secured away from children, fire, etc, plug it in and leave it until the powder is the consistency of flour. It took me about two hours in my polisher.
Once you have the black powder ground down, you need to cut the ping pong balls into tiny pieces. Why ping pong balls? Because they are made of nitrocellulose. What is nitrocellulose? I don't really know but you need it to make this so just use ping pong balls. I used a spice grinder to cut the balls up. You could just use scissors but you want to jet them as small as possible so that they dissolve faster. Once they are cut up, put them in a jar and fill it just over the top of the pieces with acetone. Let the pieces in the acetone for as long as it takes for them to dissolve, stirring them occasionally with a piece of wood. Once it is gooey and dissolved, mix in the black powder until it is about the consistency of creamy peanut butter.
Step 3: Nichrome Wre
Nichrome wire is a nickel and chrome alloy which has the property of producing heat when electricity is run through it. Being the kind of person who hates to buy something if I can scrounge it, I looked for things that use nichrome wire and found that it is what the coils in hair dryers are made of. I found that there are two types of coils that are used. One is a circular coil and the other one is a zigzag. I chose the zigzag because it stretches out perfectly for this project. The pictures show the zigzag type. Try to choose a dryer with the smallest gauge coils as these will be easier to bend and sill heat up fastest.
Step 4: Modifying the Firecracker
Now that you have the wire and the goop, it is time to make the electrical detonation system. First, take about an inch of the nichrome wire and stretch it into about two inches of wire. The pictures show using the zigzag wire. If you use the circular wire, you will need to modify this process. Once the wire is stretched, bend it at the center as shown.
Next, take a black cat or equivalent firecracker (not too big, you just need to pop the condom (that's what she said)) and cut off the end as shown. Make sure that you expose the powder core of the firecracker. Now take a small glob of the goop and smear it on the end, getting it into the core. Take the bent wire and stick the bent point into the goopy core. Once the wire is in, smear a little more goop on the end to cement in the wire. Let this dry completely, overnight is best.
Step 5: Blood!
I experimented with several types of blood and settled with just plain food coloring and water. I tried different solutions of corn syrup and things like that which make good fake blood for other applications but for the squibs, they seemed to take to long to soak into the fabric of the shirt. Here is an example:
After trial and error, I settled on water as the medium. I used a combination of a lot of red and a little bit of blue. Play around with the amounts and test it by dripping it onto a paper towel to see what it will look like soaking in.
Step 6: Assembling the Squib
Now that you have all of the components, it is time to assemble the squib. Take a condom and put some blood in it. You don't need too much, about a quarter cup or less will work. Then tie the condom off, making sure that it isn't budging too much so that it can lay as flat as possible. Tape the condom onto the cardboard as shown and then tape the firecracker onto the condom. voila! A squib!
Once you have the squib assembled, affix it to the skin with duct tape. Make sure that the cardboard side is against the skin so that the firework is separated from he skin by the rest of the squib.
Step 7: Power Source
The last part of the project is the power source. I found that using one 9v battery was not enough to get the heat the nichrome wire quickly enough for an instantaneous explosion. Three 9vs seem to work perfectly. At this point, it is a matter of wiring it the way that works for you. You basically just need three 9vs wired to a switch or button with the leads open. Get some sort of double wire with alligator clips on each end. Connect one side of the wires to the squib and one side to the leads of the power source, plug your ears and flip the switch. BANG!
The reason that I leave the leads of the power source open instead of just wiring them to long wires is for safety. My safety procedure for this involves checking to make sure that the power source is off and the clips are not attached to the power leads, attaching the clips to the squib and then to the leads. This way you are sure that the wire is not hot when you attach it to the squib.
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