Evidence Response Training: Cyanoacrylate Fuming

Learn how super glue, when heated, clings to fingerprints in the FBI's Evidence Response Team Basic course.

Video Transcript

Tom Duffy, FBI Evidence Response Team Unit: Cyanoacrylate–which is really super glue–what it does is adheres to surfaces, which makes sense it's an adhesive. By introducing heat to it, we change the liquid to a vapor. And that's what we do in these chambers you see behind us.

These are field expedient chambers you can make with about five dollars worth of material So you can use it out there in the field. It's field expedient but it works. We've taught this overseas for instance to third-world countries.

What we do is we have a chamber–we want to contain the fumes. We add heat to it, so it becomes vapors. And it flows around if you will all the items. And all the exposed surfaces to the vapor–the super glue locks onto the moisture and it coats it.

What we teach the students here is that we do it in 30 second, 60 second, 90 second increments. Less is better. Because just think of my hand here as a 3D object. All the ridge details are there. You can't really see much but if you shine a flashlight you can kind of see the print. What the super glue does is adheres to it. If you put too much on there–what happens is it fills in the gaps and now you've got a nice smooth surface and you've gotten rid of the ridge detail that you want.

You know the contrasts and surfaces. So by putting a little bit, it brings up the ridge detail just enough where it stands out from the surface and then the lab later on can apply powder to it ultraviolet lights, so on and so forth. That brings out the print to enhance it and identify it. So we want to put a protective coating over it. But not so much that we're losing the entire print.

Another benefit of that is that once you have that coating on there, if you do it right– you can see the prints with a naked eye or flashlight and it protects it from being smudged or damaged. It gives a little more degree of security that nothing is going to happen to it before it gets to the lab.


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