The Home Scientist 006 - Forensic Fingerprinting I: Iodine Fuming

[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.

[13rugrat]

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

[OnlyInNaziGermany]

@13rugrat Beg

[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.

[timothyp2009]

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

[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]

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.

[yahoorif]

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

[blueduderanch]

ninhydrin is carcinogenic isnt it, and i comes up with a purple colour. we use it to visualise amino acids.

[TheHomeScientist]

No. According to all the MSDSs I've checked, ninhydrin is neither a known nor anticipated carcinogen.

[blueduderanch]

oh right, i thought it did because it had a risk R45 on the paper we were handed out for our lab work. thought i better be safe than sorry.

[TheHomeScientist]

I just checked MSDSs from JT Baker and other sources and didn't see any R45 listings for ninhydrin. Anyway, an R45 risk factor has to be taken in context. There's a big difference between minor short-term exposure to a substance and heavy, long-term exposure. For example, asbestos is a carcinogen, but only with constant exposure to relatively high concentrations over extended periods, but brief exposure in a lab setting would almost certainly harmless, particularly if one doesn't inhale dust.

[blueduderanch]

awesome, thanks for clearing that up.

[personperson666]

nice video

[Gokumarathon]

Wow, using simple stuff to get fingerprints

I though it was very hard and advanced

5/5