Most people's fingers carry a coating of perspiration and oil. When fingers come into contact with any relatively smooth surface, they leave a print of the friction ridges in the same manner as a rubber stamp. When you brush powder lightly over this surface, it sticks to the oil and perspiration and brings out the pattern. Dusting is ideal on polished wood, metal, glass, plastics, formica, and tile. It is less than ideal, but still may work, on paper, cardboard, and leather.
Powders vary in their color, stickiness, photographic and magnetic qualities.
The most common colors are black, white, grey, aluminum, red, and gold. The best color to use is one that is the sharpest contrast with the background. For example, a white or grey powder works best on a dark surface, and a black powder works best on a whiter surface. When you expose the dusted object to ultraviolet light, the powder will glow, making the print show up regardless of the background color. Finely ground iron particles are suspended onto the surface using a magnetic wand.