erved and compared. Various powders and
chemicals are used for this purpose. When a latent print is plainly
visible, it should be photographed before any effort is made to
develop it.

No attempt should be made to brush or apply powder to prints in dust,
obviously greasy prints, or bloody prints, as this will almost surely
destroy them. Objects which have been wet or immersed in water may
still bear identifiable latent impressions. Before any examination is
attempted, however, the object must be dried.

Powder brushed lightly over a latent-bearing surface will cling to
grease or moisture in the ridges of a latent print, making it visible
against the background. Obviously, a powder should be used which will
contrast with the color of the surface. Photographic contrasts should
also be considered.

A gray powder and a black powder are adequate for latent print work.
Many fingerprint powders of various colors and compositions are
available from fingerprint supply houses but none are superior to the
gray and black.

A very small amount of powder is placed on the brush for application
to the surface. Once the contour of a print is visible, the brush
strokes should conform to the direction of the ridges. All excess
powder should be brushed from between the ridges. Too much powder and
too little brushing are the chief faults of beginners.

Gray powder is used on dark-colored surfaces. It is also used on
mirrors and metal surfaces which have been polished to a mirrorlike
finish, since these surfaces will photograph black with the
fingerprint camera.

Black powder should be applied to white or light-colored surfaces.

Aluminum powder affords the same contrast as the gray. Gold and red
bronze powders, although of a glittering appearance, will photograph
dark and should consequently be used on light-colored surfaces.
Dragon's blood powder is a photographically neutral powder and may be
dusted on either a light or dark surface.

On clear transparent glass, either gray or black powder may be used,
it being necessary only to use a contrasting black or white background
when photographing.

Prints should be lifted after photographing. Both rubber and
transparent tape are available for this purpose. Rubber lifting tape
is procurable in black or white 4" x 9" sheets and has the adhesive
surface protected with a celluloid cover. A black powder print should
obviously be lifted on white tape and a gray powder print on black
tape