Bullet hit squib device

A movie squib is typically a flat, disc-shaped explosive weighing 0.5-1.0 grain (0.03-0.06 g) — by comparison, a party popper is about 0.25 grain (0.015 g), and a small firecracker is about 2.5 grain (0.15 g) — is used to create entry or exit wounds with 10-30 ml of fake blood, respectively.^[12] This amount also depends on the absorbency of the fabric and the desired visual aesthetic. The blood is filled in a small balloon, packet, or condom placed on the squib, followed by a grooved protective plate and padding.^[13][11] The assembly is secured with duct tape, leaving a small front window for the simulant to burst through.

Various simulants, such as fake blood, water (rehearsals),^[14] glycerine (night scenes),^[15] or dry substances like dust^[16][17] and feathers (gunshot aesthetic on a down jacket),^[18][19] are used depending on the desired effect. The bullet hit squib assembly weighs approximately 30 g, measuring 50 mm in diameter and 15 mm thick. Aligning the bottom half of the blood packet with the squib produces an aerosolised burst followed by a stream of fake blood.^[20]

Dead-character costumes

An actor checks the placement and the secureness of blood squibs beneath his costume.

The actor with exploded blood packs over his costume after filming.

Dead-character costumes are stage clothes worn by actors who play characters that are killed off, modified to conceal special effects equipment such as squibs and wiring, taking into account script and scene requirements, squib integrability, aesthetics, lighting and budget. They therefore play an important role as a figurative canvas, portraying the violence and death through bursts of blood, frayed bullet holes and the staining of the clothing. For bare skin gunshot wounds, prosthetics may be used instead. For main characters, several stunt pieces with squibs and pre-scored bullet holes are prepared for multiple takes and camera angles, in addition to the hero piece used in prior scenes and closeups without squibs.

To create the bullet holes, the fabric is weakened by cutting,^[8] sanding,^[11] scoring,^[21] grating^[22] or plunging a scoring tool,^[23] often required by health and safety legislation, then loosely glued or taped back together. Squib placement should be consistent across all stunt pieces, and each costume is typically used once per take, though some clothing like jackets (e.g. waterproof, parka and down) can be reused if the bullet holes are already cleanly precut. They can be wiped clean and reset for multiple takes, making them a preferred choice in addition to their ability to conceal devices, provide padding, support multiple squibs, and be easily worn and removed, minimising the risk of accidental premature rupturing. However, stronger fabric requires more weakening and/or a more powerful squib if the fabric is not precut earlier.

Assembly and costume donning

To ensure fake blood propels outwards and within the costume, squibs are aligned with the precut bullet holes and securely attached. They are connected to a trigger, power source, and sometimes a programmable controller for synchronisation. Electronics can be placed in the clothing or off-camera. Test fires and rehearsals are performed to check for faults and to make adjustments (e.g. timing or amount of fake blood) as needed.

The actor can wear the prepared outfit immediately prior to the shot, throughout a scene, or even the entire day,^[24] depending on the number of hero and stunt duplicates available, how long the scene is, and as long as the actor is comfortable. Therefore, it is crucial to use a two-step ignition procedure with a safety controlled by the actor and crew to prevent accidental triggering.^[8] Squibs can be triggered wired or wirelessly, with the latter solution allowing for more mobility and self-contained electronics.

• Bulge visibility of bullet hit squibs embedded in tight and loose fitting clothing (labelled)
• 
  15 g of fake blood in each device beneath a cycling jersey.
• 
  Loose, thin and light-coloured fabric. Each squib contains 15 g of fake blood.
• 
  Padded jacket with dark-coloured fabric. 25 g of fake blood in each squib.

Firing the bullet hit

25 g of fake blood first bursts out accompanied by a puff of smoke (left), followed by a laminar stream of blood flowing out of the hole (right).

Safety instructions and timing of squib explosions are informed before filming to ensure the actor is comfortable with the stunt.^[8] The actor should avoid looking at the squibs and keep arms away.^[24] When triggered on cue (e.g. a specific line in the script, countdown or location), the squib detonates, bursting the blood packet and ripping open the pre-made bullet hole as the actor reacts, creating a convincing effect.

After the take, technicians check for misfires. If this occurs, power is disconnected, circuits are rechecked, and squibs replaced if needed. Spare stunt costumes minimise downtime. If successful, the wardrobe department photographs the "aftermath" for continuity and prepares for the next take, scene, or clean up.^[10][25] Bullet holes may be enhanced for the following scene.^[10] Unused costumes modified with squibs are not usually returned to the costume shop due to the damage from pre-scoring the fabric and the opening of the interior (in the case of jackets).

Post-production

Sometimes, to minimise the visibility of squibs and scoring marks on the fabric, footage is cut to just before squibs fire. Alternatively, digital removal in post-production using reference frames and content-aware fill is also possible to some extent.^[26][27] Additionally, sound effects further enhance the effect during post-production.