   BULLET HIT SQUIB  v1.05
   ~~~~~~ ~~~ ~~~~~  ~~~~~
   Updated:  Feb. 12, 1995


Introduction:

   Squibs used for on-body bullet hits function more like an air bag
inflater than a miniature land mine.  The traditional method is to
place a very small explosive called a squib behind a fragile bladder
filled with stage blood.  The squib is roughly comparable to an
electrically fired Class C common firecracker.  The bladder is confined
so that some of the blood is forced to escape though a small opening
when the squib is ignited.  A prepared hole is opened in the garment by
the expelled blood.  To the best of my knowledge no one uses the force
of a powerful explosion to burst unadulterated fabric.  Some commercial
devices use only compressed gas to propel the blood rather than
pyrotechnics.  Even though the action is explosively fast, the trick is
more a matter of gas powered hydraulics than brute explosive force.  My
article on the bullet hit squib effect explains how to do this in
detail using materials readily available in the US.

History:

   There have been several inquiries on rec.pyrotechnics about making
squibs and how to use them with a blood pack to simulate a bullet hit.
A few folks have offered needlessly dangerous advice such as using a
glass squib.  One person described how he nearly set himself on fire
with a poorly designed device.  I have seen little useful information
offered on how to do this effect from scratch on the internet.

   This article describes a reasonably safe and easy to build device.
Materials and construction methods have been limited to those available
to nearly anyone.  Unless otherwise noted all techniques described in
this article have been tested.  This article was first posted to
rec.pyrotechnics in October of 1994.  Some updates and general editing
have been done since the original posting.

Safety:

   Handling pyrotechnics and in particular placing pyrotechnic devices
on or about someone's body is inherently risky.  This device expels
material with considerable force.  Some of the supplies described in
this article can cause severe injury and property damage if
mishandled.  Before attempting to use this blood pack on a person you
are advised to build and ignite several examples under controlled
conditions from a safe distance to become familiar with it's operation
and prove your construction methods.  There are additional safety
precautions though out this document.  Follow the instructions
carefully.  Proceed with caution.

Common Sense:

   It is not possible for me to predict the limits of creative idiocy.
For those who are foolish enough to snort liquid hot melt glue or poke
themselves in the eye with a sharp stick no amount of safety
instruction would suffice.  If you are a klutz or a fool please do not
try this effect.  I have attempted to note only those hazards which are
extraordinary and or may not be obvious.  I can not anticipate all of
the potential dangers or legal implications related to the use of this
device.  Use your head.  Don't do anything crazy.

Legal I:

   The squib described in this document contains more than the 50mg of
explosive powder used in a Class C firecracker.  It may be classed as a
destructive device like pipe bombs and other such nasty things. Consult
your local law enforcement agencies and or fire code authorities
regarding the enforcement of regulations in your jurisdiction.

Legal II:

   If you severely injure someone with a pyrotechnic device great
hoards of lawyers shall descend upon thee.  Ye shall be poor for the
rest of thy days.

Legal III:

   This information is based on the opinions and experience of the
writer.  If you apply these techniques you are on your own.  Only you
can be responsible for your personal safety and the safety of others
involved in your activities.  It is your responsibility to determine the
suitability of these techniques for your application.  Use professional
help rather than attempting anything you are unsure of.  There are no
warranties expressed or implied.


   PROPELLANTS
   ~~~~~~~~~~~

   Four commonly available powders were tested for the squib.  Pyrodex
(R) and Black Powder are sold by many sporting goods stores in one
pound jars or cans (approx. $15US/lb).  Newco (R) Flash Powder is sold
in 1oz two part kits at theatre supply houses and magic shops (approx.
$11US/oz).  For the supply impaired, it is possible to make a
serviceable squib from ground match heads.  Exotic explosives are not
needed or recommended for this project.  Smokeless gunpowder burns much
too slowly to use in the squibs described in the document.

Pyrodex (R):

   Pyrodex (R) is a Black Powder substitute sold in sporting goods
stores though out the US.  The two most common grades are P and RS.  P
is the finer grade used for pistols.  RS is the courser slower burning
grade used for rifles and shotguns.  The grade of Pyrodex (R) you start
with makes no difference in performance once it has been ground for use
in a squib.  Pyrodex (R) is relatively soft and easy to grind.  Because
it is classed as smokeless propellant by the US Department of
Transportation, Pyrodex (R) is sold by more sporting goods stores than
Black Powder.  It is more difficult to ignite than Black Powder by
conventional means such as muzzle loader percussion caps or hot wires.
It may also be less likely to ignite while being ground but I have no
formal data to support this assertion.  Pyrodex (R) burns much slower
than the equivalent grade of Black Powder when unconfined or lightly
confined.  In muzzle loading fire arms the burn rate is crudely similar
to Black Powder.  Pyrodex (R) is slightly less smoky than the
equivalent grade of Black Powder.  There is at least one other Black
Powder substitute on the US market, Black Canyon Powder (R).  I have
not used Black Canyon Powder (R).

Sporting Black Powder:

   Goex (R) is the most common brand of sporting Black Powder in the
US.  There is at least one other brand of real Black Powder sold in the
US, Elephant Brand (R).  Some cities in the US have banned the sale of
Black Powder.  As a general rule it's easier to find Black Powder for
sale in smaller towns.  Sporting Black Powder comes in various grain
sizes from Fg coarse to FFFFg fine.  Grains coarser than FFg and finer
than FFFFg are specialty items not often seen on the shelves of random
sporting goods stores.  FFg is used for most large bore rifles and shot
guns.  FFFg is used for most pistols and small bore rifles.  FFFFg is
the finest and fastest burning grade commonly sold.  FFFFg is most
often used to prime flintlocks.  The grade of black powder you start
with makes no difference in performance once it has been ground for use
in a squib.  FFFFg is much easier to grind than courser grades.  Black
Powder is slightly hygroscopic.  It can draw some moisture from the
air.  Always store Black Powder in a tightly sealed container.

Newco (R) Fast Flash Powder:

   Newco (R) Fast Flash Powder is used for theatrical special effects.
It comes in a two part kit of fuel and oxidizer.  Newco (R) Fast Flash
Powder is very fuel rich.  The kit contains 2/3 fuel and 1/3 oxidizer
by weight.  This is a slow, bright, and smoky Flash Powder compared to
some of the more potent mixtures of flash or salute powders used by
display pyrotechnists.  Newco (R) Flash Powder burns VERY fast
unconfined compared to the other powders listed in this document.
Modest quantities of flash powder can explode unconfined.  Flash powder
is sensitive to heat, spark, friction and impact.  Attempting to grind
flash powder will not improve it's burn rate and is extremely dangerous.

        ****  NEVER GRIND FLASH POWDER!  ****

Ground Safety Match Heads:

   This is the powder of last resort.  Even when ground to a fine
powder match heads burn slowly compared to the other powders listed.
Removing match head material from the stick and grinding it is a
tedious and somewhat risky procedure.  Attempting to grind strike
anywhere matches would be futile.  Strike anywhere matches are very
friction sensitive by design.  Wooden kitchen matches are easier to
work with than paper.  For testing Fire Chief (R) brand wooden kitchen
matches were used.  The easiest way I have found to remove the material
from the match stick is to crush match the head with a pair of needle
nose pliers.  Crush the bigger chunks of match head material with
pliers before using the mortar and pestle.  Safety match heads are
fairly tough to grind.  They are easy to ignite while grinding.  See
the section on grinding for more instructions and precautions.


   GRINDING
   ~~~~~~~~

   Pyrodex (R) and Black Powder burn faster and give off less smoke the
smaller the grain size is.  The home made igniter described elsewhere
in this article is too small to use on raw Pyrodex (R).  Ground match
heads burn just barely fast enough to make an explosive squib using the
confinement method described later in this document.

   One of the more risky aspects of this project is grinding the
Pyrodex (R), Black Powder, or match heads.  I recommend getting a real
mortar and pestle for this job.  A mortar and pestle can be bought few
a few dollars US at a hobby shop or a scientific supply house.  There
is a fair risk these powders will ignite while grinding.  An improvised
mortar might shatter from the thermal shock if the powder ignites.  If
you grind only one of the the three substances listed, the risk of
being injured is slight.  There are several safety precautions you
should take...


Grinding Safety:

        Grind with as little pressure as is needed to do the job.

        Keep away from flammable materials and ignition sources.

        Wear leather (not plastic) gloves and eye protection.

        Hold the mortar away from your face and body.

        Grind only very small batches .6cc (1/8 table spoon) or 12 match
        heads or less per batch.  A pinch of ground Black Powder is
        fairly energetic if ignited.  Igniting such small amounts of
        unconfined ground Pyrodex (R) or match heads is about as violent
        as setting off a full book of matches.

      * Most important.  Keep the all other powders sealed and far away
        from the grinding operation.  A pound of FFFFg Black Powder or
        an ounce of Flash Powder ignited in close proximity to your body
        could ruin your whole day.  Not very likely to be fatal, but it
        could easily put you in the hospital and do permanent damage
        to tender parts of your body.

        ****  NEVER GRIND FLASH POWDER!  ****


   IGNITER
   ~~~~~~~

Materials:

        Lead Wire:  Single strand copper telephone wire .51mm
        diameter (24 AWG).  This wire is commonly used for interior
        phone wiring in the US.

        Bridge Wire:  Single strand copper wire .16mm diameter (34
        AWG).  The individual strands of wire in common 18 AWG lamp cord
        are 34 gage.

Construction:

   Take two pieces of phone wire 125mm (5") long.  Cross the wires at
90 degrees about 6mm (1/4") from the ends.  Pinch the long ends of the
wires in one hand.  With your other hand grab the short ends of the
wires.  Twist and pull the short ends of the wires till you have about
13mm (1/2") of wire twisted together in a tight rope like spiral.  You
should have formed a small fork at the end of the twisted section.
With a sharp knife cut though the insulation all around at the bases of
the forks.  Cut as close to the twisted section as you can without
shorting the two wires.  Strip the insulation from the end of the forks.

   Put the assembled lead wires in one hand.  Grab about 13mm (1/2") of
the thin bridge wire with the same hand.  Wrap the bridge wire tightly
five turns around the exposed end of one lead wire at the base of the
stripped section.  Run the wire to the other fork and wrap it five
turns.  The bridge wire should span only about 1mm (1/32") between the
forks.  Trim the excess lead and bridge wire from the end of the forks.

Assembly Note:

   The bridge wire and the stripped end of the phone leads should be
bright metal like a new penny in order for this to work reliably.
Clean the wire with a sharp knife or steel wool if needed.  I have not
done any testing of the shelf life of these igniters.  Oxidation may
degrade their reliability over time.

Power Source and Testing:

   These igniters need about 12 volts at 2 amps the work reliably.  A
12 volt battery charger or auto battery is recommended as a power
source.  Other than the few inches of lead on the squib, wiring should
be fairly heavy.  Use 7.5 meters (25 feet) or less of 1.02mm diameter
(18 AWG) or heavier wire for reliable ignition.  To test your wiring
energize a bare igniter using the same set up as you would use in the
completed device.  The bridge wire should give off a small spark and an
audible pop when energized.  If it only glows and or smokes you will
need more power.  Use heavier gauge wiring, shorter wiring, and or a
stronger power source.

   Under normal circumstances 12 volt circuitry is safe to handle.
Under extraordinary conditions people have been electrocuted by lower
voltages.  Using equipment with greater than 12 volts potential in
close proximity to someone's body would be unnecessarily risky.  Take
care that all electrical circuitry is completely isolated from the
performer at all times regardless of the voltage of the equipment used.

Car Battery Safety:

   If you use a car battery keep sparks and other ignition sources away
from the battery.  Car batteries release hydrogen and oxygen gas which
is an explosive combination.  A typical 12v auto battery can deliver
several hundred amps to a dead short.  This is enough current to heat
1.02mm diameter (18 AWG) wire white hot if shorted.  Use caution around
a car battery.

Igniter Limits and Alternatives:

   These home made igniters will not reliably ignite raw P Pyrodex (R)
or smokeless gunpowder.  They will work well with FFg or finer grained
Black Powder, Flash Power or ground Pyrodex (R).  You may be able to
adapt the squib described later in this document to use an Estes (R)
rocket igniter.  Estes (R) igniters are more fragile and expensive than
home made.  The leads are short and uninsulated.  An Estes (R) igniter
needs much less current to operate and will light less sensitive
compounds.  A wide variety of other commercial igniters, electric
matches, and ignition squibs available from theatrical and pyrotechnic
supply sources.

Home made Low Current Igniters:

   I chose copper bridge wire mainly because it is readily available
and inexpensive.  The reason this design requires so much current is
that copper conducts electricity too well.  A higher resistance bridge
wire will generate more heat from a given current source.  Commercial
ignition devices typically have an bridge resistance of approximately 2
ohms and can be ignited with a current of about .5 amps.

   A low current home made igniter can be made with nichrome wire in
place of the .16mm diameter (34 AWG) copper bridge wire.  Nichrome wire
is a special order item and was not tested for this project.  Someone
one the net suggested using a strand of steel wire from COARSE steel
wool for a low current igniter.  Thin steel wire should work fine but I
have not tested this method.  Very fine steel wool like 0000 is too
fine to use.  Ultra fine wires do not have enough mass to generate
sufficient quantities of heat for reliable ignition.

Performer Activated:

   It is generally better to have this device triggered remotely by
someone other that the performer whenever possible.  Actors have enough
to worry about without having to fiddle with effects gadgets.  For some
applications offstage triggering may not be practical.  For a
mechanical triggering it would be best to use two switches.  Use one
switch to arm the device and a second to trigger the squib.

Sound Activated:

   Although I have not experimented with this myself it is possible to
trigger a blood pack with a sound activated system.  There are many
designs and kits for sound activated switches from various electronic
sources.  Using a sound trigger could be a bit touchy.  The device
would have to be sensitive enough to fire when it detected a gunshot
yet ignore all other sounds.  A performer's dialog or other sound very
close to the microphone could be as loud as a blank fired from a
distance.  A switch to arm the triggering device just prior to use
would reduce the chance of accidental triggering.

   Some commercial squib devices use radio remote control ignition.

Compact Power sources:

   Of commonly available battery types, NiCad batteries put out the
most current for a given size.  Alkaline batteries are the next most
powerful compact current sources in common use.  A small battery back
could easily be concealed under a costume.


   SQUIB
   ~~~~~

Safety:

   This squib is small electrically ignited explosive about as powerful
as a Class C firecracker.  While it is not capable of dismembering or
even removing a digit it is not completely harmless.  Don't set one off
in your ear or any other body opening.  Exploding one close to your
face could result in eye injury.  EYE PROTECTION IS RECOMMENDED while
constructing these squibs.  I doubt the squib described here would
break the skin if set off in your hand.  I'm not foolish enough to try
setting one off in my hand to confirm this.  From memory I can say that
a Class C firecracker exploded in the hand is about as pleasant as
being struck by 16oz hammer.

Squib Size:

   It is important that the squib be only of sufficient strength for
the purpose.  Using too large an explosive introduces the risk of
burning or puncturing the performer.  Larger squibs made by this
technique tend to give off more light and smoke.  Most real bullets
don't flash or smoke on impact with a human.

   Any explosive device large enough to blow a hole in common fabrics
is also large enough cause serious injury.  A method for preparing a
garment with a pre-weakened hole is described later in this document. I
strongly discourage using any explosive device with sufficient power to
break though unadulterated clothing for a bullet hit effect.  The use
of more powerful explosives could result in large and unsightly holes
in your performer.  A powerful explosive would also tend to turn the
stage blood into a fine mist rather than a somewhat more realistic
splatter.

Smoke:

   For this application the squib should give off as little smoke as
possible.  Ground Pyrodex (R), ground Black Powder, or ground match
heads give off very little smoke in the quantities used.  For a given
volume, Newco (R) Fast Flash Powder is the smokiest powder listed.
Because very little Flash Powder is needed for these squibs smoke
should not be a problem.  Most of the smoke, flash and sound produced
by these tiny squibs is absorbed by the stage blood in the final
assembly.

Casing Design:

   A special grade of ultra-thin walled HDPE tubing is used for the
casing of the squibs used in this project.  My design for squibs uses
a length of common plastic drinking straw 6.4mm (1/4") diameter as a
case.  The ends are pinched shut and sealed with hot melt glue.  To
compensate for different powders, different lengths of drinking straw
and quantities of powder are used.  Glad (R) brand drinking straws
purchased at a local super-market were used for testing.  The straws
were 6.4mm (1/4") outside diameter with a measured wall thickness of
196 microns (.0077").

Glue Gun Safety:

   I unable to ignite small samples of the four powders listed with hot
glue or the tip of my trusty Swingline (R) glue gun.  I don't believe a
properly functioning hot glue gun gets hot enough to ignite these
powders.  If your gun is running so hot that the glue smokes and
bubbles you may have problems.  Take care not to spill the powders into
or on the glue gun.  When using the construction method described
below, explosive powders need not come in contact with hot glue. Always
work with very small supplies of powder.  Igniting a full container of
powder would be a BIG problem.  Resist the temptation to touch fresh
hot melt glue.

Squib Assembly:

   Consult the chart below for the appropriate length of drinking
straw.  Cut the required length of drinking straw.  Put a 3mm (1/8")
diameter drop of hot melt glue in one end of the straw.  Quickly pinch
3mm (1/8") of the straw shut with a pair of pliers.  Hold the straw
shut with the pliers for about a minute till the glue cools.  Fill the
tube HALF FULL of the powder selected using a small piece of paper
folded to form a trough.  Insert an igniter so that only the tip is
immersed in the powder.  Place a healthy glop of hot melt glue on the
open end of the tube.  A larger amount of glue is needed on the end of
the tube the leads exit though to seal around the wires.  Quickly pinch
the tube shut with pliers.  Hold the squib shut with pliers for about a
minute till the glue cools.

Half Full:

   The squibs are only half filled because flame can propagate faster
though loose powder.  This will let the powder burn quicker.  These
squibs work more efficiently with the case half full than they would if
the case were completely filled with powder.

Squib Powder Sizing Chart:

   To compensate for the difference in the powders used, consult the
chart below.  All of these loads yield approximately the same results
when used in the blood pack described later in this article.  There is
no need to actually weigh the powders for assembly.  The approximate
weights are given for reference only.  To measure the powder cut the
straw to length seal one end and fill HALF FULL with the powder.


     Powder  Used               Straw Length    Approx. Powder Weight
-----------------------------+----------------+-----------------------
Ground Match Heads              32mm   1 1/4"    181mg   2.8 grains

Ground Pyrodex (R)              25mm   1"        214mg   3.3 grains

Ground Black Powder             19mm   3/4"      103mg   1.6 grains

Newco (R) Fast Flash Powder     13mm   1/2"       71mg   1.1 grains


* These powders are listed in ascending order of burning speed.


Special Note for Ground Match Heads:

   This step is needed for ground match head squibs only.  Because
ground match heads burn so slowly the stage blood will quench the
powder before much of it has a chance to burn.  Additional confinement
is needed to shield the match head powder while it burns.  Cut a 9cm (3
1/2") strip of cloth tape.  Place the end of the squib in the middle of
the strip running lengthwise.  Fold the tape in half length wise to
where the gummed face sticks to itself.  Seal the squib in the tape
with the lead wires running out where the two ends of the tape meet.
The drinking straw alone is sufficient confinement for ground Pyrodex
(R), ground Black Powder, or Newco (R) Fast Flash Powder.


   STAGE BLOOD
   ~~~~~ ~~~~~

   You can buy ready made stage blood from theatrical supply houses or
magic shops.  It is also widely distributed in the US at Halloween
time.  Buy it cheap as a clearance item after Halloween.  Make your own
for blood a few dollars US a pint (500ml) with ingredients from any
super-market.

Stage Blood Formula:

    4 parts - Karo (R) clear corn syrup or equivalent.
    2 parts - Chocolate syrup.  Hershey's (R) or equivalent.
    1 part  - Red food coloring.  Durkee (R) or equivalent.
    1 part  - Water
    1 drop  - Blue food coloring per 59cc (1/4 cup).

   For a one cup batch use a 1oz bottle of red coloring, 2 tablespoons
of water, 4 tablespoons of chocolate syrup, 4 drops blue coloring and
fill the balance of the cup with corn syrup.  Mix well.

   In my humble opinion this formula looks good on skin and fabric. You
may wish to fiddle with the ratios a bit.  I did not spend a lot of
time dialing in the formula.  In limited testing this stage blood did
not stain cotton clothing.  If you splatter it around indiscriminately
you are on your own.  I doubt it will come out of wall paper, carpet,
drapes, and such.

* This blood formula does temporarily stain skin.

Other Bloody Tricks:

   Edible stage blood in gelatin capsules held in the mouth and bit
open on cue can make a good bloody lip effect for fist fights.  I have
read of putting a blood capsule up the nose for a bloody nose effect. I
have not tried a blood cap up the nose.  Empty gelatin capsules in
various sizes are sold by many pharmacies in the US.

Safe Blood

   The blood pack described later in this document does splatter
blood.  Avoid situations that would project splattered blood into a
performer's eyes.  The edible blood formula I have described is
nonflammable and should not be harmful to the eye.  Don't use a blood
formula that contains alcohol, other flammable liquids or soap in a
squib fired blood pack.  Strong soap in the eyes can be extremely
dangerous.  A flammable formula could be ignited by the squib.  If you
use commercial stage blood it should be nonflammable and nontoxic. Read
the label of commercial products.  Test any stage blood you are unsure
of for flammability.


   BLOOD PACK
   ~~~~~ ~~~~

Materials:

        Metal plate 10cm (4") square.  The example I've been using is
        18ga steel 1.4mm (.056") thick.  Any metal plate sturdy enough
        that it can not be bent with your bare hands should be heavy
        enough.  The edges of the plate should be de-burred smooth with
        a file and or sandpaper.

        Squib described elsewhere in this document.

        Cloth tape 5cm (2") wide.  I used common duct tape for testing
        Duck (R) brand.  Any good quality cloth tape will probably
        work.  If you can get it and or have money to burn you can use
        gaffer's tape.  Gaffer's tape is easier to remove and leaves
        less residue than duct tape.

        79cc (1/3) cup stage blood.  A formula for making your own
        stage blood is in this document.

        A latex condom.  Get the cheapest plain prophylactic you can
        find.  Trojans (R) brand non-lubricated condoms were used for
        testing.  You may be able to substitute a toy balloon.

Assembly:

   Fill the condom with 79cc (1/3 cup) of stage blood.  Release the air
and twist the condom until it is roughly spherical.  Tie the condom in
a knot.  Cut off the excess condom with scissors.

   Place a piece of tape in the center of the plate to insulate the
plate from potential electrical shorts.  Tape the squib to the center
of the plate with the leads oriented diagonally to one corner of the
plate.  Use two small pieces of tape on both ends of the squib to cover
any sharp edges on the squib.

   Lay out four 15cm (6") strips of cloth tape STICKY SIDE UP on a flat
surface in a square pattern.  This should be in a tic-tack-toe pattern
with an 19mm (3/4") hole in the middle.

   Place the blood filled condom ball in the middle of the tape layout.
The knot in the condom is oriented to the side.

   Place the plate squib side down on the condom.  Squish the condom
until it is about 19mm (3/4") thick.  The condom should bulge out
nearly to the sides of the plate.  Hold the plate as flat as possible
while pulling the ends of the tape over the back of the plate.  Press
the tape to the back of the plate all around.  The leads for the squib
should exit from a corner of the plate.

   Take four 10cm (4") pieces of tape and seal the blood pack around
the edges.  These strips should be placed with half the width of the
tape on the back of the plate and half of the strip wrapped around to
the front of the blood pack.

   The finished blood pack should be about 19mm (3/4") thick with the
condom squeezed into a 9cm (3 1/2") diameter by 19mm (3/4") thick
disk.  The front of the assembly will have an 19mm (3/4") square of the
condom exposed centered over the squib.  The condom bladder need not be
pressed into a perfectly circular disk.

Action:

   When the squib is ignited approximately 25% of the blood should be
ejected though the hole in the tape in the front of the blood pack.  As
the stage blood escapes it opens the prepared hole in the garment.  The
balance of the stage blood is left behind to leak out at a more
leisurely pace drenching the performer.  The stage blood should absorb
most of the smoke, flash, and sound of the squib explosion.

Testing:

   If when you test this assembly the tape gets torn by the explosion
you are using too large a squib or tape that is not strong enough.
Tearing of the tape by the squib explosion indicates a problem that
will need to be corrected before you attempt use this device on a
person.  For initial testing ignite from a distance of 3 meters (10
feet).  Water can be used instead of stage blood for preliminary
testing.  If the condom does not break well see the trouble shooting
section below.


TROUBLE SHOOTING
~~~~~~~ ~~~~~~~~

   This design worked well for me with my particular set of materials
assembled as described.  Several design factors were balanced for a
successful effect.  Slight changes to the components can cause subtile
and frustrating reactions.  You may have to compensate if you make even
relatively trivial alterations.  My squibs were conservatively set up
to be just powerful enough to burst the condom cleanly.  Variations in
powders, squib case strength, quantity of stage blood, condom brand,
size of the backing plate, and other factors may reduce the reliability
of the design.

Prototypes:

   There were several design attempts that failed while I was
developing this technique.  Using a 76mm (3") plate and 57cc (1/4 cup)
of blood did not work well.  In the design described earlier the condom
is under quite a bit of stress before the squib is fired.  In a smaller
device the condom is not as pre-stressed.  A more powerful squib and
possibly a stronger packaging system would be needed to burst a condom
containing less blood.  You might also be able to stretch a condom with
a smaller amount of blood by twisting it more before tying it off to
get a similar pre-stress effect.  Sandwich bags may be more fragile
than condoms.  Sealing and sizing a sandwich bag is problematic.

   I tried using more blood with the 10cm (4") plate and found this to
be too much for the condom and plate size combination to handle.  There
are many brands of condoms on the US market.  I only tested a couple of
brands.  I'm sure that some condoms are easier to break than others.

   As described in this article my squibs had just enough energy to do
the job.  Using a slightly larger than listed amount of Newco (R) Fast
Flash Powder I had problems with the squib being too powerful.  The
tape was shredded by the force of the explosion.  Using too small an
exit hole in the blood pack has a similar effect.

Powder of last resort:

   Using ground match heads as propellant was added with some
reservations.  A friend said he had made firecrackers with matches
years ago so I figured I'd give it a try.  Even though I was able to
get this powder to work it would not be my first choice.  I left this
in for the benefit of those who can not easily obtain better supplies.
There is a section dealing with slow burning powders after the powder
selection chart.

Case Strength:

   One person using ground Pyrodex (R) reported an incomplete powder
burn problem similar to my first attempts using match head powder.
Apparently there is quite a bit of variation in the wall strength of
drinking straws from one brand to the next.  If the powder is not
sufficiently confined it will not have a chance to burn completely
before the blood quenches it.  Making a larger squib with the same case
material and powder will not necessarily give you a more powerful
explosion when used in a blood pack.  If you have trouble with the
condom not breaking cleanly try a different brand of drinking straw or
use the tape reinforcement method described after the powder selection
chart.  Faster burning powders should give a bit more leeway on case
strength requirements.

Case Materials:

   I choose drinking straws for casing because they are inexpensive,
easy to obtain, easy to work with and reasonably safe for use in this
effect.  When a straw shatters the fragments are fairly light and not
sharp.  Using light weight case materials is important for safety.
Light weight fragments will not travel very fast for a significant
distance.  Because the fragments are light they can not deliver much
energy on impact.  Heavier or more dense case materials can become
dangerous projectiles when a device is exploded.  Avoid metal, glass,
hard plastics and similar substances if you choose to develop another
casing design.  You would be hard pressed to find a less expensive or
easier to work with casing for hand made squibs than a drinking straw.


   SETUP
   ~~~~~

   Once you have made and tested your blood pack you will need to
prepare the garment.  Place the garment face down on a cutting board.
Cut the hole in the cloth with a fresh single edge razor or similarly
sharp implement.  If you have a surgeon's touch you can leave a few
strands of material to hold the opening shut.  You can cut clear though
the material then bind the hole shut with small pieces of Scotch (R)
tape.  Either of these techniques can leave a completely invisible hole
if carefully done.  A hole may not needed if you are not using this
effect close up.  Not using a hole in the garment for a stage
production should reduce the amount of splattered blood to clean up
from the stage and make the wardrobe folks a little happier.

   I recommend starting with a tight fitting tee shirt as a base to
tape everything to.  Cover the area where the blood pack will be placed
with a piece of leather about 20cm (8") square.  A piece of rubber
floor mat or heavy vinyl covered cloth may be substituted for the
leather protective pad.  Tape the blood pack to the center of the pad.
Put the prepared outer garment on.  Check the alignment of the hole and
the blood pack. Run the wires out the back, down a pants leg, or
wherever is appropriate for your application.


   EXPERIMENTAL
   ~~~~~~~~~~~~

   This squib design only costs a few cents US each to make.  When
making your own squibs you can easily customize them for different
applications.  This section contains suggestions for further
development.  These are not completely tested items.  Experiment with
these at your own risk.  Beware of fire hazards and flying debris from
squibs.  Take care with sets, props, costumes, performer's hair, and
any other flammable items near your squibs.


Pico Squib:

   In the real world entrance wounds from gun shots tend to be quite
small.  The entry hole from a typical hand gun or rifle is about the
same size as one would get from stab by a pencil.  To simulate a more
realistic entry wound it may be practical to make very small squibs
with about one tenth the powder using a coffee stirrer or swizzle stick
as casing material.  The smallest of these straws I have found is
2.4mm (.100") inside diameter.  It should be possible to make extremely
mild squibs with this tubing.  Mounted on the surface of a blood pack
a tiny squib could be sized to have have just enough energy to break
the condom and open the prepared hole in the fabric.  I have not tested
this idea.  Casing fragments may be a safety problem.

Exit Wounds:

   Exit wounds from a high powered weapon can be huge.  To simulate a
massive exit wound you might try using several squibs behind a zip-lock
sandwich bag of blood.  Colored tissue paper could be used to simulate
shredded viscera.  The backing plate and protective pad would have to
be scaled up for a large blood bag.  With some effort a relatively flat
and concealable device could be designed to simulate a large exit wound.

Smoke Squib:

   For a small puff of smoke with minimal flash try FFg Black powder in
a modest sized squib.  You could also mix powdered sugar and ground
Black Powder for a quick burning smoky mixture.  Slit the casing to
reduce sound.

Flash Squibs:

   Flash squibs may be handy in places where you could not not hide a
conventional Flash Pot.  For a small bang and flash in midair you could
make a Flash Powder filled squib.  Suspend it by the lead wires or
support on a wire stalk.  Flash Powder squibs could also be useful for
simulating electrical equipment failures.  Add a dash of iron filings
for extra sparks.  Iron filings can be had free from auto shops that do
brake jobs.


   EPILOGUE
   ~~~~~~~~

   This article was written with several things in mind.  First, I
wanted to know how this effect was done myself.  The method I have
devised is based on experimentation and information gleaned from many
sources.  Second, I have seen posts from several people speculating on
how to do this.  Some of the techniques suggested were unreasonably
dangerous or ineffective.  Third, I hate how to articles that seem to
go out of their way to use hard to get supplies, exotic equipment, and
tedious procedures.  If you have access to better supplies than those
mentioned and you are able to make appropriate adjustments by all means
use them.

   As it stands now this is more a cook book of suggestions than a
universal solution.  I may do additional development of this effect in
the future.  I will not attempt notify everyone of updates.  The most
current draft is available via Email on request.

   I am not a professional writer.  It's been years since I've earned
my living in a theatre.  If you find any errors, omissions or unclear
instructions please let me know.  There are many possible variations on
the basic techniques I have described.  Any comments or suggestions for
improvements are welcome.


         murr rhame       /\/\ |_| |~ |~      murr@vnet.net
         Show-Fire entertainment pyrotechnics mailing list.
