Development Fingerprints with Fingerprints Powders

Powdering is the application of finely ground, colored powder to a nonporous object to make latent prints visible. Powder clings to moisture, oil, and other residues.

Fiberglass filament brush (Fig. 1a), magna brush wand (Fig. 1b), cotton, paper.

Materials and Chemicals
• Powders — black, magnetic powder (Fig. 2)

Fig. 1. Brushes: a) fiberglass, b) magna brush wand

Processing Procedure
Nonmagnetic Powders

  • Pour needed amount of powder into a small pile.
  • Dip tips of bristles of brush into powder.
  • Apply a small amount of powder onto the surface and begin to brush.
  • Brush in the direction of any ridges that begin to appear.
  • Build powder onto ridges and stop when latent print reaches point of sufficient clarity.
  • Clean excess powder from between ridges using brush or cotton.
  • Use cotton to process large areas by dipping cotton into powder and lightly wiping over the surface. When outline of the latent print becomes visible, stop using the cotton and switch to the brush to complete the development.

Magnetic Powders

  • Place magna brush wand with magnet engaged into container of magnetic powder.
  • This will produce a bristle-like effect at the end of the wand when withdrawn.
  • Apply in a circular motion to the surface being examined. Make sure that only the
  • magnetic powder touches the surface, not the wand.
  • After the print has been developed, hold the wand over the container and withdraw the control rod. This will disengage the magnet and release the powder.
  • Re-engage the magnet and pass the clean wand over the developed latent print and
  • the surrounding area to remove excess powder. Do not touch the surface.

Fig. 2. Powders: a) nonmagnetic, b) magnetic