Amazing Super Glue

Super glue is a marvellous substance. However, it took a while for me to realise just how fantastic it is. I admit it, I’ve been using the stuff for years without really understanding it’s wonderful versatility. An episode of the BBC TV show, Death in Paradise, finally convinced me (Cultbox, 2011). The detective solved a murder case using a fish tank and a tube of amazing super glue. So, just what is Super glue?

What is Super Glue?

Properly called cyanoacrylate, Super Glue is a quick-setting, strong bonding, adhesive. It works by polymerisation rather than the usual method of sticking using solvent evaporation (Dictionary, 2023).

Image 1: Polymerisation of super glue

The correct formula is C₅H₅NO₂. The presence of water triggers the polymerisation, shown in image 1. Pretty much everything you intend to bond has a trace of water on its surface. Even the air carries water as humidity (Neer, 2001).  The trick is pressing together the surfaces you need to bond fast enough.

How is Super Glue made?

Super Glue starts its life as ethyl cyanoacetate. This is heated in the presence of a non-reactive gas such as nitrogen, and then formaldehyde is added to break down the compound into gaseous monomers. This gas is collected in cooling pipes and cleaned up with base scavengers and free-radical inhibitors to ensure it remains in liquid form until needed (History of Glue, 2023).

When exposed to water, monomers polymerise and form the strong bond we know as Super Glue.

How was Super Glue discovered?

There’s an urban myth going around that super glue was invented as a surgical glue. Unfortunately, this is just a rumour. Like a lot of advances, the adhesive was discovered when the military got involved. Super glue was an accident.

Image 2: Dr Harry Coover, inventor of super glu.
Public doman.

In 1942, Harry Coover, shown in image 2, attempted to create an improved plastic for precision gunsights. His research on cyanoacrylates created a sticky plastic that was too difficult to work with so he moved on to better things. It wasn’t until 1951, that he realised the adhesive potential of his creation. It bonded permanently, without the use of heat or pressure (Lemelson-MIT).

But everyone knows Super Glue was used for surgery

Not Quite. Coover continued his work on  Super Glue, and in 1964 he applied to the US Food and Drug Administration (FDA) for wound closure.

However, cyanoacrylate is toxic.  The polymerisation reaction is exothermic and the heat generated can damage tissue. Not only that, but during polymerisation, formaldehyde is produced which can cause eye, skin, and respiratory irritation (Kwon, 2018).

Here is where the medical legends appear, without FDA approval surgeons in the Vietnam War sprayed Cyanoacrylate over wounds to stablise them. This stopped the bleeding so wounded soldiers could be evacuated to a field hospital. It is credited with saving many lives (O’Brien, 2021).

To address the toxicity issue if the alcohol of Super Glue is changed from a methyl or an ethyl to a butyl or an octyl then it becomes less toxic to tissue (Neer, 2001). The FDA approved this version and it is available to the general public as a ‘liquid bandage’ (O’Brien, 2021).

Whoops, I’ve Super Glued my fingers together

So yes, Super Glue does bond skin. But don’t worry. Try soaking your fingers in warm, soapy water, or a little acetone. After that, try to pry apart your digits with a non-sharp tool. Please don’t pull the fingers apart or you might rip your skin (Neer, 2001).

Hold on, you started this article with a detective solving a crime

The really amazing thing about Super Glue is how many accidents have led to new ideas for its use. As I said above, the fictional Detective used cyanoacrylate fuming to develop fingerprints on a non-porous surface, in this instance, a glove. He headed tubes of super glue in a fish tank and solved his case

Image 3: Fingerprints on a glass.
Public domain

So, how did we learn about Super Glue and fingerprints? 1977, a Japanese hair and fibre forensic scientist, Fuseo Matsumara, used super glue to mount a hair on a microscope slide. While looking down his microscope, he saw a fingerprint developing on his slide. He talked to his colleague Masato Soba who went on to develop the technique we know as Cyanoacrylate Fuming.

When heated, the cyanoacrylate forms a gas which condenses on the oils and moisture of fingerprints producing a white crystal around the lines and whorls (Fingerprint Fuming, 2023). Further information on fingerprint techniques can be found in this article.

Conclusion

Ever since I saw that episode of Death in Paradise I have been fascinated by the properties of Super Glue. When reading for my MSc in Forensic Science I finally learned the technique the detective performed. Seeing the crystals emerge on the glass slide felt like pure magic. So, from failed gunsights to crystal fingerprints, it’s all in a day’s work for Amazing Super Glue.

References

Cultbox, (2011). ‘Death in Paradise: Series 1 episode guides. Cultbox.co.uk . November 15. https://cultbox.co.uk/spoilers/episode-guides/death-in-paradise-series-1-episode-guide

Dictionary, (2023). Superglue. Merriam-Webster. https://www.merriam-webster.com/dictionary/superglue

Fingerprint Fuming. (2023). Science World. https://www.scienceworld.ca/resource/fingerprint-fuming/#:~:text=This%20technique%20was%20developed%20in,that%20he%20mounted%20using%20superglue

History of Glue, (2023). History of Super Glue – Facts about Super Glue. GlueHistory.com http://www.gluehistory.com/glue-origin/history-of-super-glue/

Kwon, A. (2018). Super Glue Which Saved Wounded Soldiers on the Battlefield. Communicating Science. https://blogs.ubc.ca/communicatingscience2018w111/2018/11/10/super-glue-which-saved-wounded-soldiers-in-the-battlefield/#:~:text=Fast%20way%20to%20stop%20bleeding%3A%20

Lemelson-MIT. Harry Coover. Lemelson-MIT.edu https://lemelson.mit.edu/resources/harry-coover

Neer, K., (2001). What makes super glue so super?. HowStuffWorks.com. 6 August. https://home.howstuffworks.com/question695.htm

O’Brien, C. (2021). How World War II Led to the Invention of Super Glue. Military Times.  July 30. https://www.militarytimes.com/off-duty/military-culture/2021/07/30/how-world-war-ii-led-to-the-invention-of-super-glue/

Images

Properties of superglue https://en.wikipedia.org/wiki/Cyanoacrylate#

Coover https://commons.wikimedia.org/wiki/File:Harry_Wesley_Coover_Jr.png

Fingerprints https://commons.wikimedia.org/wiki/File:Dusting_for_fingerprints.jpg