The Home Scientist 006 - Forensic Fingerprinting I: Iodine Fuming

Use a tiny amount of crystal iodine (or substitute drugstore tincture of iodine) to reveal latent fingerprints on paper and other porous surfaces. Iodine fuming is the oldest method for revealing latent fingerprints, and is still in very wide use by professional forensics technicians.

More information: http://blog.makezine.com/science_room/forensics/forensics_laboratory_82_revea...

Forensic Latent Fingerprinting Kit: http://www.makershed.com/ProductDetails.asp?ProductCode=WFORKD&Click=37908

Before anyone comments, a note about pronunciation. Many scientists pronounce iodine as eye-oh-deen--by analogy to the other halide elements, fluorine, chlorine, bromine, and astatine--rather than eye-oh-dyne. Many people born before 1940 pronounce it eye-oh-dinn. Any of the three is correct.

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[eveningniteshade]

Does anyone know what powder is best if you want black fingerprint, maybe due to a white background? Baby Powder is easy enough to find, but I don't know what would be used for the black powder?

[TheHomeScientist]

@eveningniteshade

Lampblack or soot is a good choice. Fill a beaker or test tube with cold water, light a candle, and hold the glass container just above the flame. You'll get a nice black deposit of lampblack.

[yahoorif]

could it be fatal if I accidentally inhale the iodine vapour?

[TheHomeScientist]

Inhaling any significant amount of iodine vapor can certainly be harmful, but we're only using a milligram or so of iodine crystals, which isn't enough to present any risk.

[eemtek]

do you think iodine fuming would work on a porous rock? had some kid break all the windows in my sons car.. cops say they dont have the tech to get fingerprints off the rock found in the car. I'd like to give them one, its going to cost a couple thousand to fix, and my son soundnt be the person to pay for it.. I have kept the rock safe and not touched or handled.

[OnlyInNaziGermany]

@13rugrat Beg

[timothyp2009]

@eveningniteshade ... graphite is also good, but as eveningniteshade said, soot is pretty much the best.

[13rugrat]

his voice puts me to sleep thumbs up if this happens to u

[quantumdude]

Simple trick to remove iodine stains is to wash the surface with a diluted solution of sodium thiosulfate or sodium bisulfite. The former can be found in pet shops where it used as a dechlorinator for fish tanks.

[yahoorif]

ok, but I still gonna put on my chemical mask.