Academic journal article Forensic Science Communications

Vacuum Metal Deposition (VMD)

Academic journal article Forensic Science Communications

Vacuum Metal Deposition (VMD)

Article excerpt

Vacuum metal deposition is used to develop latent prints on nonporous specimens and some semiporous specimens (e.g., magazine pages and photographs). The vacuum metal deposition technique involves coating or depositing a thin layer of metal onto a surface by thermalizing metals under vacuum.

Vacuum metal deposition developed prints are fragile. Extreme caution should be exercised when handling and photographing these specimens.

These procedures are for a specific vacuum metal deposition chamber size. Various styles and sizes may require different procedures.

Equipment

Vacuum metal deposition chamber, control card or test sample

Materials and Chemicals

* Gold

* Zinc

Processing Procedure

1. Place or suspend the specimen from the interior rack. Secure the specimen to the rack with magnetic clips. A control card or test sample should also be placed on the interior rack. If the specimen needs to be rotated, remove the rotation probe and place in a plastic holder.

2. Place gold in the appropriate boats, using all six boats if the specimen needs to be rotated, but only the second, fourth, and sixth if processing only one side. Check the boats for stress cracks. If damaged, the boats need to be replaced. Contact designated maintenance personnel for appropriate replacement. The total amount of gold to be thermalized for each sequence will be approximately 0. …

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