Good
chemistry is key formula for recent stop-motion movies
With Halloween coming up and two new dark animated movies in theaters,
Inside Science delves behind the scenes and straight into the polymeric goo that
make these movies ooze off the screen.
(October 19, 2005) -- College Park, MD Tim Burton's "Corpse Bride" and
Nick Park’s “Wallace and Gromit: Curse of the Were-Rabbit”,
released earlier this month, are stop-motion animation films with a new scientific
twist behind the scenes. Both new and old stop motion shows are comprised of
sets and characters made of malleable, vibrant-looking but lifeless material.
Stop-motion is a cinematic form
of animation, in which handcrafted puppets are moved just fractions of an inch,
frame by frame, in front of still cameras so they can be seamlessly played back
as one continuous video or film.
Unlike stop-motion animation projects in
the past,
including movie classics such as 1933's King Kong and the TV pop-icon of the
60's, 70’s and 80’s, "Gumby," materials used today to build
a creepy cast of puppet players has merged art with science.
The cast of lifelike creatures in "Corpse Bride" were made using
new and user-friendly components. Modern chemistry has brought today's animators
tools that can compete with sophisticated visuals generated by the latest computer
graphics programs. These modern state-of-the-art hybrid plastic skins include
injected foam-latex and high-tech urethane that can then be painted with a wide
range of color pigmentation. In fact, technicians had to hand craft the "Corpse
Bride" dolls and stretch "skins" of silicone over steel-reinforced
armatures.
According to Clay Western, vice president of a company that supplies materials
like rubber and plastic for movie props and special effects, this next generation
of stop-motion animation materials has been, in many ways, developed specifically
for the movie business “to meet the needs and address the problems most
commonly encountered by make-up, special effects, and puppet-animation artists,” said
Western, of the Smooth-On Company in Bethlehem, PA.
Limits of endurance
The traditional forms of latex and urethane had limitations: they didn't last
as long as it took to shoot the movie and couldn't stand up to the tiny repetitive
motions that stop animation entails" said Western. The constant using of
a character's body - arms, legs, and head - cause great stress in the materials,
he said, "and after so many repetitive movements, materials like rubber
show signs of wear." The wear would be apparent on a giant movie screen.
The materials used for the technique of stop-motion animation in both Corpse
Bride and Curse of the Were-Rabbit is suited to meet the needs and demands of
filmmakers and behind-the-scenes technicians. The technology allows an old-fashioned
type of story telling – stop-motion animation -- through using current
materials.
According to Western, Dragon Skin and its newer forms vary somewhat in elasticity.
There are four main areas of concern to the movie make-up artist and on-set animator: “stretchability,
thickness, color and opaqueness.” The material used is not just any old
silicone, but a material Western says is, nicknamed "platinum silicon." Platinum
silicone is still not easy to ascribe to one of the three major states of matter
--solid, liquid, or gas. Silicone, for the most part, can exist simultaneously
as both a liquid and a solid. Sometimes, silicon is more solid than liquid depending
on how it is mixed, treated and what other chemicals or conditions (such as extreme
heat, for melting) which may be applied.
Overall, the greatest advances have been made in just the past three to five
years. Silicone skins and hybrid polymers are markedly advanced in their ability
to sustain repetitive movement. The "platinum" silicone skins are said
to have the advantage of being fairly durable. The silicones can often withstand
a relatively broad range of temperature fluctuations. They do well under varying
degrees of light exposure and can exhibit very good tensility, longevity, and
can endure almost non-stop human handling.
Think of silly putty: at first, when you open
up the hard plastic egg that encases it, you find a hard, dry, almost rubber-ball
like substance. After a few hours of being stretched, pulled, dropped, soaked,
and so on it can become more like a big old wad of recently discarded chewing
gum!
What makes today's scientific formulations of materials different from those
used in the past?
"A lot," said former make-up artist
and current director of media for the American Plastics Council, Rob Krebs.
Hollywood dynasties of families ruled the makeup world so the formulas, of the
Bau family and others, became secrets to help the family earn money… The latex foam
ingredients were experimented with and experimented with until they got foam
that basically wrinkles like skin, folds like skin and allows the actor to move
his face as naturally as possible, and took makeup but did not dissolve under
the lights. When they had the right 'formula' that was a family secret. Some
formulas absorb light so differently that you could tell where the appliance
ended and where the actor’s skin began --and it looked fake. Others were
more natural and those people were successful."
The science of spooky effects
Chemical engineer Greg McKenna is a professor of chemical engineering at
Texas Tech University, is an expert in the field of rheology, the study of science
of deformation and flow of matter.
The methods used by make-up and effects artists from decades ago, while sounding
much like a bad chemistry experiment gone awry, or alchemy dating straight back
to the Middle Ages, is nevertheless a science. When asked for his view on some
of the work done in the early days of special effects makeup and puppet or stop-motion,
model making, McKenna asserts that the kind of experimentation done behind the
scenes by effects artists and animators was in fact, very much, like real chemistry
and physics. "Really," said McKenna, "this [was] science in its
roughest form... What these artists were doing was very much like cooking, and
cooking, is, as you know, a science. It's chemistry."
Rheologists like McKenna
often come from chemistry and chemical engineering backgrounds. But there are
many qualified rheology experts with backgrounds in some of the other sciences,
like physics and biology. Some experts involved in rheology work more on the
theoretical side and may have advanced degrees in mathematics. Some industrial
arenas and manufacturing corporations in which the rheologist may work, often
as a consultant, are responsible for making, supplying or integrating any of
a wide variety of polymeric materials. From engineers and other scientists working
to improve safety features on vehicles, to cosmetics manufacturers who make wearable
products, such as false eyelashes, acrylic gel fingernails and instantly drying
nail polish--- rheologists study just about anything and everything that is readily
available or convertible from liquid states of matter to solids, and back again.
As far as rheology and its experts are concerned, the materials involved in special
effects makeup and polymers used in puppet molding for stop-motion animations
are all considered fair game for their expertise.
Inside Science News Service extras!
More information
Chris Rowe
crowe@aip.org
American Institute of Physics
301-209-3136 Dr. Gregory McKenna, Department of Chemical Engineering
Texas Tech University
Lubbock, TX 79410
(806) 742-4136
Mr. Rob Krebs
Rob_Krebs@plastics.org
American Plastics Council
Arlington, VA 22209-2307
703-741-5626
Smooth-On
Easton, PA 18042
(610) 252-5800
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