Certain surfaces have such a texture that even with gelatin lifters, it is hard to lift powdered fingerprints in their entirety. Examples are: Hammerite painted coin boxes and polystyrene packaging material. In these cases, white or black silicone rubber casting compound can be used. The casting compound is mixed with hardener and diluant (if needed) and poured over the print developed with fingerprint powder. After the silicone rubber has cured, the fingerprint is lifted.
Depending on the color of the fingerprint powder that was used, white or black silicone rubber is used for contrast.
Silmark Black is used for lifting of fingerprints developed with fingerprint powders. Light coloured fingerprint powder, for example the regular or magnetic silver or white coloured ones, contrasts well against the black background that this silicon material provides.
SILMARK, black, 150 g in tube, with 20 g paste hardener
Silmark white is used for lifting fingerprints which are developed with dark fingerprint powders like Swedish Black and Magnetic Black. The white colour of the silicon material offer a contrasting background for dark coloured fingerprint powders.
Silmark is also available in grey and brown for the casting of toolmarks.
SILMARK, white, 150 g in tube, with 20 g paste hardener
Silmark CART for lifting fingermarks
Available in black, white, and clear
Silmark CART is a 2-part addition curing silicone compound in a cartridge. Silmark CART is available in various colours: gray and brown for toolmark casting and black, white, and clear for lifting of powdered fingermarks. Using the dispensing gun the compound is easily applied to textured surfaces like Hammerite painted metal and polystyrene packing materials. There is no need to manually mix the two components, this is done by the static mixing tip which is mounted on the cartridge prior to each use. With the optional spreader tip attached to the static mixer a 25 mm/1 inch wide strip of silicone material is applied over the fingermark to be lifted.
A sheet of silicone paper can be applied to the silicone material shortly after applying it to the surface containing the fingermark. Gently rubbing the back of the paper ensures the silicone material is fully pressed into the texture of the surface. This will not only assist in getting the powdered fingermark off the surface as complete as possible, in many cases it will also provide a flat backside of the lift which makes it easier to handle during photography. The paper adheres to the silicone lift and offers ample space to make notes on. Setting times vary with temperature, with ambient and material temperatures of 20°C/68°C this is around 4 minutes and some 8 minutes at 10°C/50°F.