Friday, May 21, 2010

Guest Blogger: Sirchie Powder - Invisible Detection Powder

1) Many things react to a UV light. If you go to the Sirchie website, there is a manual about UV lights that lists many of the things that the lights react to. Included in the list is Vaseline (because it is petroleum based), cosmetics, waxes, and bodily fluids (including things like sweat stains on clothes) . This is extremely important (especially here in a tropical climate) because things like sweat glow, and we all know that even when it is cold, people in high stress situations sweat. Many products' reactions to UV light are similarly colored, so it is not necessarily clear what product is glowing. Also, different color Sirchie powders glow different colors. There is also dual wave length powder that glows 2 different colors depending on if a short wave UV light is used or a long wave UV light.

2) Photographs can easily be taken of the reaction that is seen in UV light. All that is needed is a camera that can have the flash turned off.

3) There are also specific wax crayons that are used to mark areas that react. This means that if powder is on a t-shirt, the area that glows can be marked and the t-shirt can be saved for evidence to later show exactly where the reactions occurred. This is stated in the fluorescent powder manual from Sirchie. The company suggests that it is done to preserve evidence. The manual also suggests that officers make clear notes of exactly what they saw.

4) Contamination - It is very fine powder--finer then baby powder. When you open or close the lid, a cloud of powder forms each time. The manual suggests gloves and protective clothing because it gets everywhere. One of the properties of the powder is that is has great adhesion qualities. This means that it is not easily wiped away and it will stick to whatever it can. And, the contamination is hard to see without the aid of a UV light. So, after a package is sealed, then it should be checked with a UV light, the officer's clothing should be checked for contamination since they are presumably going to later pick that box back up.

- Kathleen Wright, Investigator

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