Detailed Procedure:

Typically, ceramic tile is glazed and therefore nonporous. The most productive sampling areas for ignitable liquid residue on a ceramic tile floor are grout, moldings, pre-fire surface cracks, and absorbent materials (rugs, clothes, etc.) found on top of the tile inside the burn pattern area.

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To collect ceramic tile:

1. Photograph the pattern area on the ceramic tile.

2. Wear eye protection, breathing protection, and wear new, unused, clean latex or nitrile gloves. Use protective gloves (properly cleaned or new) if necessary to prevent cuts.

3. Select a sampling area on the inside edge of the pattern, preferably in a grout line, at a baseboard, or on a pre-fire crack.

4. Use a properly cleaned or new tool (hammer, cold chisel, screwdriver, pliers, trowel) to chip out a sample from the selected area. Chisel down to the subfloor, if possible.

5. Using gloved hands or a clean tool (ie: trowel), gather chipped fragments into a new, clean metal paint can. Leave at least 1/3 headspace in the can. Also collect the subfloor below the ceramic tile. If it will fit in the same can, add the subfloor to the tile sample. If the piece is large, break it into smaller pieces to fit into the container. If the subfloor will not fit in the same can as the tile to leave 1/3 headspace, place the subfloor in a second can and note on the evidence label that it was the subfloor and what tile sample it corresponds to.

6. Clean the lip of the can using a new or properly cleaned screwdriver or other suitable tool.

7. Tightly close the can by gently tapping it with a rubber mallet to seal it. Do not dent the can because it may compromise the seal.

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

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

10. If possible, collect a comparison sample of tile and subfloor that is not suspected to contain ignitable liquid residue. To find comparison samples, locate a protected area of ceramic tile away from the suspected pattern area. It is best to collect comparison samples from another room, not the room of origin. Change gloves between each sample and follow the same procedure described above, collecting the fragments with a new or properly cleaned tool into a different new, clean metal paint can. Collect sections of tile, grout, and adhesive.

11. 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.

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Laboratory testing of ceramic tile for ignitable liquid residue:

Gas chromatography mass spectrometry can be used to identify ignitable liquid residue in the sample. Comparison samples are used to exclude compounds found naturally in the tile floor, grout, and adhesive.

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Source:

IAAI. A Pocket Guide to Accelerant Evidence Collection, 2nd Edition. Massachusetts Chapter, International Association of Arson Investigators, 1999. Online version: http://www.interfire.org/res_file/aec.asp#gla