Movie special effects usually come with a big price tag. They can be complicated, requiring specialised (and licensed) skill sets. Some are also very dangerous if not performed correctly. Blood squibs are no exception. They’re the packs that you see explode whenever somebody gets shot in a movie or TV show.
Traditionally, squibs hold a small explosive charge that detonates on demand. You’ll generally need to be licensed in order to create and use them, and there are all kinds of safety checks. There are safer options, though. Such as this one shown in this video from John Hess at Filmmaker IQ. We see us how to make our own (relatively) safe squibs using a very minimal list of ingredients..
There are commercial air powered squib options out there. But there’s nothing like making your own, and as Hess describes it, it’s fairly simple to do. Do note, that compressed air can still be dangerous. Hess states in the video that as little as 12PSI can blow out an eye. And you’ll need about 20PSI for this effect. It’s not that complicated, though. Here is the list of basic materials.
- A 6-8ft length of 3/8″ rubber tube
- Gaffer tape
- Velcro strips
- A hot glue gun
- A 3/8″ barb
- 1/8″ NPT connector
The first part of the assembly is the squib itself. To one end of the hose, we push in the 3/8″ barb and secure it with a hoseclamp.
We need to plug the other end of the tube. This is done using a hot glue gun. You don’t need to create a large plug. Hess suggests around half an inch.
The plugged end is where the squib will eject its contents. A hole needs to be cut into the tube to allow it to spread out. Cut a third of the way through the tube just below the plug. This cut needs to be straight. A second cut is made at an angle, forming a sort of V shape when viewed from the side.
With the hole cut, it’s time to make the mount to attach it inside the talent’s clothes. This is done with a couple of strips of gaffer tape, with the pipe sandwiched between. With both pieces attached, you’ll want to cut out a hole in the tape to match the hole in the tube. Then attach the hook portion of the velcro strips to the gaffer tape on either side of the tube. You’ll want the tape on the same side as the opening for the “blood” to come out.
That’s the delivery system complete. The next thing to decide is exactly how it will get its air pressure. There are a couple of ways you can go. You could go expensive and get an actual air compressor. This will require a trigger for each squib to enable the flow of air going into it. Or, you can go for a cheaper, lighter, more mobile solution using CO2 canisters, a tire inflator, a tank valve to 1/8″ NPT connector and a 1/8″ to 1/8″ NPT coupler.
If you need to be mobile, the c02 canister option is much easier to work with. But you are quite limited in use. Each squib will require its own canister, and once the canister’s spent, you’ll need another to do another take. With an actual air compressor, you’ll generally get a lot more power, that will allow it to fire several squibs off a single unit. And you’ll also get a lot more control over the exact pressure being sent into the tube.
Whichever method you choose to power it, the method for attaching and using it is pretty much the same. With the velcro hook side look on the squib itself, the loop side attaches to the inside of the subject’s clothing. You’ll then want to cut a small slit in their clothing that lines up with the hole in the tube. If you don’t do this, then anything spraying out of the tube will simply build up on the inside of their clothes.
You may want to use more tape, or elastic bands and belts to help secure the system to your subject. With that much tubing, it can easily become dislodged if just relying on a couple of strips of velcro.
Finally, it’s time to roll cameras, shout action, and hit the squibs at the right time. One thing Hess mentioned that I found quite interesting was to have the subject wear a red t-shirt shirt underneath their clothes. This helps to create a stronger blood presence once it explodes.
It may not hold up to Quentin Tarantino’s scrutiny, but a very effect pack for ultra low budget productions. For stills or video, it looks pretty effective. You can tailor the “blood” spatter by adjusting the amount stored in the tube, as well as the air pressure of the compressor.
And, again, remember, compressed air can still injure you, so do this at your own risk, and be careful!
I’m not sure I’d ever have a need for a squib for my own work, but a very cool and simple idea nonetheless.