You've probably seen or read about this before in books or on TV; the grizzled old detective steps into the scene of the crime and sees the lighter/handgun/baseball bat left behind by the criminal. He gets to work, likely yelling at a couple members of the forensics team in the process, and starts to close in on the perpetrator.The detective is then promptly kicked off the case, possibly due to some trick by the villain, and the case is closed. Unable to shake the feeling that the crook got away he takes the evidence home, and with the power of super glue extracts a perfect fingerprint and catches the nefarious villain.
But how does it work? Well, super glue is made of cyanoacrylate, a substance that, when heated to a vapour, reacts with the oily residue left behind by the pores of the finger to create a clear image of a fingerprint on a piece of evidence, such as a gun. if the evidence is put in a heated airtight container with high humidity along with super glue the super glue will boil away into the immediate atmosphere and will eventually settle on the residue left behind by the finger. The reaction gives the residue a whitish appearance, making the fingerprint easy to see.
Step 1: What You Need:
- A non-flammable, easy to seal box; If possible heat-resistant plastic or metal would be best, since a cardboard box like I used seems to absorb some of the moisture.
- Duct tape or masking tape
- Small container (to hold hot water)
- Super glue
- A heat source, such as an incandescent light bulb (I used the base of a lava lamp)
- A piece of "evidence" with a fingerprint on it (smooth, hard materials like plastic, metal and glass work best)
Step 2: Preparation
- Form the tinfoil into a rough dish shape, or just crumple it into a ball and make an indent with your thumb.
- Cut a small hole in the side of the box to accommodate the power cord of your heat source.
- Place the tinfoil dish as close to the heat source as possible, and place the small container opposite it.
- Put your evidence between the tinfoil dish and small container.
Step 3: Developing the Print
- Turn on your heat source and allow it to warm up.
- Boil some water and fill your small container with it. This will increase the moisture level in the box, making it easier to develop the print.
- Squeeze a nickel-sided drop of super glue into the tinfoil dish, then close the box.
- Tape around the lid to make the box airtight. The faster you do this the better.
- Check on the evidence after 30-45 minutes. If nothing has happened, add a little more super glue and wait another 30 minutes.
Step 4: Results
- The container you used to hold the water will have some super glue residue floating on top, so it would probably be a good idea to wash it before using it again.