Cyanoacrylate (Super Glue) Fuming


What is the Cyanoacrylate Fuming Method (Super Glue Method)?


The super glue or cyanoacrylate method is a forensic science technique that uses the vapors of super glue to develop latent fingerprints.  A latent fingerprint is a fingerprint left on a surface as a result of the oils and perspiration from the pores of the finger.  The fuming is performed in a developing chamber using super glue and water[1] which allows the vapors to adhere to the fingerprint, making the fingerprint visible. Once the print is visible, you can enhance it by using dyes or powders. Super glue fuming is a way to make a fingerprint semi-permanent so the print can be dusted (lightly brushing fine powder onto the residue left by a fingerprint) and tape-lifted (use tape to put over the developed fingerprint and lift the print and place onto a fingerprint card) various times and not be disturbed or ruined.


The main steps in fuming a fingerprint are:

1) Putting super glue and water into the developing chamber on a warming plate

2) Placing the piece of evidence into the developing chamber and

3) Allowing time for the fingerprint to develop. 


In order to determine the length of time to develop a fingerprint, a control print can be used.  An oily fingerprint can be placed onto a plastic baggie or a piece of aluminum foil.  Then as the prints develop, the control print can be watched to determine the amount of time the evidence should be left to develop.   A latent fingerprint examiner or a person trained in fingerprint evidence is qualified to perform the fuming of fingerprint evidence.

How does the Cyanoacrylate Fuming Method Work?


Latent fingerprints are composed of sweat, amino acids, fatty acids, proteins, potassium and sodium.  Cyanoacrylate or super glue fuming works by having a high affinity or strong attraction to the amino acids, fatty acids and proteins in a fingerprint and the vapors of the super glue adhere to these components.    


The steps in super glue fuming are as follows:

1)      A few drops of super glue (see figure 1) are put into a small, circular, aluminum container which is then placed onto a coffee cup warmer. 

2)      Water is also placed into an aluminum container on a different coffee cup warmer[2].        

3)      The piece of evidence is placed into the developing chamber (see figure 2) along with the super glue and water containers.  This results in the super glue aggregating on the print, leaving a white film on the ridges, making the print visible (see figure 3).            


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Figure 1:  Different types of super glue that can be used to  fume a fingerprint.  (Picture from The Graveyard Shift website).   







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Figure 2:  A fingerprint developing chamber. (Picture from The Graveyard Shift website).  







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 Figure 3:  A fingerprint developed using super glue fuming. (Picture from The Graveyard Shift website).








Why is the Cyanoacrylate Fuming Method Used?


Cyanoacrylate or super glue fuming is used to develop latent fingerprints and make them visible.  The sweat in a fingerprint evaporates relatively quickly while the other compounds remain in the print for a longer period of time.  The super glue method is an excellent way to develop older fingerprints because the sweat has evaporated and the super glue fumes only need the amino acids, proteins and fatty acids to develop the fingerprint.  Fingerprint powders, however, adhere to the sweat and therefore the powders have a difficult time adhering to only the amino acids, proteins and fatty acids. 


By using the super glue method, fingerprints can be obtained from uneven surfaces and hard-to-dust surfaces such as bottles, knives, guns and dead bodies.  When dusting uneven or difficult surfaces, there is only one chance to lift the print perfectly.  If the fingerprint is developed with cyanoacrylate or super glue fuming the print will be semi-permanent, therefore allowing the examiner to re-dust and re-lift the print if necessary.  Figure 4 is an example of using the super glue fuming method on a gun.  The latent fingerprints are highly visible and are ready to be dusted with fingerprint powder and lifted.



Figure 4: Latent prints developed on a pistol using super glue fuming.  (Picture from Fisher, Barry A.J., Techniques of Crime Scene Investigation, 7th ed., CRC Press, 2003). 






All crime scenes are different and therefore the pieces of evidence have to be handled on a case-by-case basis.  The cyanoacrylate or super glue fuming provides another method to obtain fingerprints from evidence.  The type of surface the fingerprint evidence is deposited on allows the examiner to determine whether dusting for fingerprints or super glue fuming is best.  Sometimes it is hard to visualize fingerprints on multi-colored surfaces because the fingerprint powder does not give a significant amount of contrast.  This would be another case in which cyanoacrylate or super glue fuming would be used.  Figure 5 is an example of using super glue fuming on a multicolored, glossy surface of paper.  The prints are easily visible, which can then be further enhanced by fluorescent dyes or powders.      



Figure 5: Latent fingerprints developed on multi-colored, glossy-coated papers using cyanoacrylate or super glue fuming.  (Picture from Fisher, Barry A.J. Techniques of Crime Scene Investigation. 7th ed. CRC Press, 2003.).  









What are the disadvantages of using the Cyanoacrylate Fuming Method? 


There are many advantages to using the cyanoacrylate fuming method but there is one disadvantage.  It is very easy to over-glue (leaving the piece of evidence in the developing chamber too long which leads to the super glue filling in the ridges of the fingerprint rendering a useless print) the fingerprint and therefore the piece of evidence needs to be closely watched when developing, especially when using water because the print develops even quicker. 


How can you enhance the super glued fingerprints?


After a fingerprint has been fumed with cyanoacrylate or super glue, there are a couple of different methods to make the print more visible.  The print can be dusted with a variety of different dusting powders such as black, white, and fluorescent powders.  These powders will be used depending on the color background the print is on.  You want to achieve the most contrast of the print with the background.  Fluorescent dyes can also be used which can be visualized using an alternate light source, which is a light delivering device that has numerous filters with different wavelengths of light. 





Cyanoacrylate or super glue fuming uses the vapors of super glue to develop latent fingerprints.  Super glue fuming is an easy and effective way to make fingerprints visible.  Super glue fuming can be performed on old or new fingerprints and can then be further enhanced by using dyes or powders.        

[1] Note:  the process described is done on a small-scale.  It can also be performed on a larger scale with a bigger chamber and larger amounts of super glue and water. 

[2] Note:  If you use a hot plate, make sure coils are not exposed as the coils of the hot plate may cause the volatile fumes of the super glue to catch on fire which can release poisonous gases.



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