Step #2: The Heating Element
- A heating element is used to speed up the rate at which the pool of cyanoacrylate vaporizes and releases its fumes into the container. This lets you develop a print in as little as 10 minutes. Without the heater, the process might take over 24 hours to complete.
- I recommend using a small 15-20 watt coffee warmer/candle warmer as the heater. Using a larger heater in a small closed space filled with combustible vapors can be a fire hazard.
- You need a small container to hold the liquid super glue while it is being heated. You want to use something cheap and disposable because each fuming will leave behind a large patch of solid glue. The tray should be non-porous so that it doesn't soak up the glue. It also needs to be able to withstand the heat of your chosen heating element.
- There are a lot of regular household items that you could use. You could use a plain metal bottle cap or fold together a piece of aluminum foil into a small tray.
An important component of fingerprints is water. This water evaporates over time making it more difficult to develop a good print. So if the print is more than 24 hours old or if the air is very dry, then you need to put a small warm water reservoir in the fuming chamber. The warm water increases the moisture level in the chamber and on the print. This helps to develop the print faster.
Step #6: Assemble the Fuming Chamber
Now it is time to assemble the fuming chamber. Open the container. Set up the heater in one corner and put the glue tray on top of the heater. Place the water next to the heater. Set up the test sample in the corner opposite of the heater. You want to position it in such a way that the area with fingerprints will be readily exposed to the fumes in the chamber. The easiest way to expose both sides is to prop the sample up against the side of the container.
Step #7: Use the Fuming Chamber to Develop Fingerprints
Once everything is in place, put a large drop (about half of a 0.07 oz tube) of super glue onto the glue tray. Turn on the heater and close up the container. Allow it to sit for at least 10 minutes. Then check on the development of the fingerprints. If the ridges of the fingerprints have developed into clearly visible white lines, then you are done and can remove the sample. Otherwise, put the sample back into the box and check on it again every 5 minutes until it is fully developed. You may need to add more super glue to the tray if the initial glue has dried up. Be careful not to let it develop too long or the spaces between each line will also turn white and make the print more difficult to read. I recommend doing several trial runs to get the hang of the process before attempting to develop any prints that you care about.