Dustprint Lifting Instrument
Safety Information
- Read all of the instructions before
using. Keep the unit dry. Do not operate in rainy or wet weather.
Do not touch the probe tip. Do not use the probe tip to touch
anyone else. Use extreme caution when lifting dust prints
from a metal surface.
- Electric shock can occur if this unit
is used improperly.
Description of Equipment
- Heavy-duty carrying case
- Dimensions: 44.7 x 29.5 x 13.3
cm (17 5/8" x 11 1/2" x 5 1/4") Weight: 6.8 kg (15 lbs.)
- Voltage output: 7000 volts
Power pack with rechargeable, sealed
lead-acid batteries AC Battery Charger Lift Film, 25 sheets,
22 x 40 cm (9" x 16") Probe Flashlight Ground Wire with Clip
Set of Bureau Photographic Scales Roller
- Transparent Scale
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Background
At crime scenes, footwear impressions in dust may be left
by the suspects. While some may easily be photographed
at the scene or in the lab by using special lighting techniques,
some are almost impossible to photograph or even to see
under normal circumstances. Dust impressions on newspapers
with all of its printing and photographs, on file folders
of a similar color as the dust, and on wooden doors and
desktops with the wood grain interfering with seeing the
image, are a few examples of the surfaces common to burglary
and other crime scenes.
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Photographing these impressions, even
with oblique or side lighting may not prove productive due to
the low contrast available and the background image interference.
Another method has been devised to transfer this dust to a dark-colored,
clean background by the use of static electricity. The electrostatic
technique of lifting shoe impressions in dust from papers, desk
tops, doors and floors has proven successful. The technique
involves placing a dark-colored piece of metallic film over
the visible shoe impression or suspected area where shoe impressions
may be and charging the film with a high-voltage probe and power
pack. This electrostatic charge causes the dust to adhere to
the metallic film. Because the metallic film is dark in color,
a suitable contrast is gained between the light-colored dust
of the shoe impression and the dark-colored film. With this
vastly improved contrast, photography of the impression is easy.
Directions for Operation
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1) Plug the red wire from the probe
into the red plug on the power unit. Plug the yellow/green
wire into either of the two yellow/green plugs on the
power unit.
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2) Cut a 2-3 inch strip from a
sheet of lift film (hereafter called the "ground film")
and tape it, silver side down, near the area with the
impression in dust. It should be taped down about 1-2
inches from the area where the new sheet of lift film
will be placed over the shoe print impression. This ground
film acts like a grounding antenna, but it is much more
effective.
3)Attach the alligator clip to
the ground film. If the clip or the ground film touches
the lift film, a short circuit may shutdown the power
pack. If this occurs, reset the power pack by turning
it off and turning it back on.
4) Place the lift film over the
suspected area with the black side against the surface.
Place the film directly over the top of the impression
but do not slide it into position.
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5) Turn on the power unit by pushing
the switch to either "Variable" or "Max." A red light
will come on, indicating the power unit is on. Do not
touch the metal tip of the probe after turning the power
unit on.
6) If the power switch is pushed
to "Variable," the Low-High knob can be adjusted to provide
more power or less power. Turn the power unit on to "Max"
to use on plastic counter tops. Use "Variable" power on
metal and other surfaces, adjusting it as needed. Attempt
to use the least amount of power. Using excessive power
can damage the lift film. When dealing with metal surfaces,
attach the alligator ground clip directly to the metal,
rather than to the 2" ground film.
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7) Touch the tip of the probe directly
to the silver side of the lift film. The ground film and
the lift film should suddenly cling to the surface beneath
it. A crackling sound may be heard.
8) While maintaining the electric
charge by keeping the probe in contact with the lift film,
use the roller to gently apply pressure on the film to
obtain the maximum contact between the film and the surface.
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9) When finished with the probe,
turn off the power unit by pushing the "Variable-Max"
switch to the center position. The red light on the power
unit will go off. Continue to hold the probe on the film
for about 5 seconds to allow it to discharge.
10) Carefully remove the lift film
and turn it over. It may "crackle" with static electricity.
Handle the lift film carefully and try to keep it as flat
as possible. For best results, transport the film taped
inside a covered box. Photograph the impression as soon
as possible. The strip of ground film may be used over
and over again.
11) It is usually necessary to
recharge the unit about every three months. If the unit
is used frequently, it may be necessary to charge it every
month or so. Plug the AC Battery Charger into the unit
and plug it into a wall outlet, leaving it plugged in
overnight.
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Helpful Hints
- If the footwear impression is on a
door or wall as the result of the suspect kicking it, tape
the strip of ground film to the surface next to the impression
and tape the lift film over the impression. Use the Electrostatic
Dustprint Lifter as usual.
If a "ground plate" system is desired,
use a whole sheet of lift film with the silver side down
and clip the ground wire to it. Place the paper item with
the footwear impression on it on top of the "ground plate"
film and place the lift film over it with the black side
down. (The two sheets of film will be black side to black
side with the paper in the middle.) Use the Electrostatic
Dustprint Lifter as usual.
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Turn the power unit on to "Max" to
use on plastic counter tops. Use "Variable" power on metal
and other surfaces, adjusting it as needed. Attempt to use
the least amount of power. Using excessive power can damage
the lift film. When dealing with metal surfaces, attach
the alligator ground clip directly to the metal, rather
than to the 2" ground film.
Handling and Storage Tips
- In some cases, the dust residue on
an impression is so heavy that the first lift is too thick
with dust and does not show all of the detail of the impression.
A second lift of the same impression should be made, because
it may appear clearer and show more detail for a successful
comparison.
The dust adhering to the metallic film
is not permanent. The footwear impression should be photographed
as soon as possible. Keep the film from coming into contact
with other surfaces and rubbing the dust off while transporting
it back to the photo studio. Tape it to a large piece of cardboard
or place it in a shallow box. It is recommended to carry it
flat at all times.
Do not roll up the used film and put
it in a mailing tube. Do not wrap it in plastic or place it
in a plastic bag. If this is done, a partial transfer of the
footwear impression to the plastic wrapping material may occur.
Long-term storage can be accomplished
by taping the edges of the film into a shallow box like an
empty photographic paper box or a pizza box (which looks rather
unprofessional) or a specially-designed footwear cast/lift
film box. The lifted footwear impression on the film should
be photographed as soon as possible, as even long-term storage
of the impression in this manner is not permanent.
- Stacking more than one piece of lift
film with impressions inside of an empty photographic paper
box is not recommended. The impressions may transfer or may
be rubbed off. Our special cast/lift film boxes come with
an insert which gives an additional layer of cardboard to
tape the lift film to. It is supported above the first lift
film so both layers of film are protected from rubbing the
insides of the box and each other.
Photography Tips
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When photographing any shoe impression,
it is imperative to have a scale in the picture. The Bureau
photomacrographic scale was designed specially for photography
of shoe print impressions. The "L" shape of the scale and
the circles printed on it help to confirm and, if necessary,
correct the placement of the camera.
A transparent scale can be used also.
Place it face down in the photograph so the numbers will
read backwards. By turning the negative over when placing
it in the enlarger to make a print, the numbers on the scale
will read correctly, and the shoe impression will be in
the proper orientation for comparison.
A medium- to high-contrast film should
be used. Do not use color films, as they do not show contrast
as well as black-and-white films.
While small-format film in 35mm cameras
can be used, medium- to large-format film cameras are recommended.
The Polaroid MP-4 and other styles of copy-stand large-format
film cameras use 4" x 5" sheet film and have methods for
controlling the amount and direction of the light.
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While side lighting or oblique lighting
can be used, superior photographs can result by using a
forensic light source, laser or other type of fiber optic
delivery cable.
Care and Maintenance of the Equipment.
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