Detailed Procedure:

 

To collect painted surfaces:

1. Photograph the item in place.

2. Wear new, unused, clean latex or nitrile gloves.

3. Wet painted surfaces should be air dried before collection.

4. The entire painted object should be collected. If the object is large, cut out a generous piece of the painted surface. Select an appropriate container for the item. Continue with Step 6 below.

5. If the painted item or a portion of the painted item cannot be collected, the paint may be carefully removed from the item. Using a new, clean tool (such as a putty knife), cut or pry away the FULL DEPTH of the smear or film, keeping all layers of the paint intact, from the topcoat down to the bare surface. DO NOT SCRAPE THE SURFACE OF THE PAINT OR REDUCE THE PAINT SAMPLE TO POWDER. Loosen the full depth of the smear/film down to the substrate. Place the sample in an appropriate leak-proof container such as a pillbox, glass vial, or evidence/pharmacy fold. DO NOT STICK THE SAMPLE TO ADHESIVE TAPE OR PACK IT IN COTTON. Continue with Step 6 below.

6. Seal the container with evidence tape. Initial and date the tape.

7. Label the container with identifying information, including case number, date, exhibit number, a brief description, and your name.

8. Store the item in a secure location, such as a locked evidence van or your vehicle, until you are able to transport it to the laboratory.

​

Laboratory testing of paint on painted surfaces:

Paint can be analyzed to determine class characteristics (color, chemical and elemental composition). Questioned and known samples can be associated on these bases. If multiple layers of paint are present, a high degree of association may be made based on the number, sequence, and relative thickness of the layers as well as the individual characteristics of each layer. It is possible, although rare, to physically match a paint fragment to a known source based on fracture edges, surface striations, and layer structures.

​

Source:

Crime Scene and Evidence Collection Handbook. Bureau of Alcohol, Tobacco, Firearms and Explosives, 2005.

 

"SWGMAT Web Site." Scientific Working Group for Materials Analysis, Website, July 1, 2013.