HOW SUPER GLUE WORKS: A simple explanation of how this amazing one-part adhesive functions.
Everyone is familiar with epoxies and acrylic resins. They are two-part adhesives that when the two parts are mixed a chemical reaction takes place that causes them to harden. They're very strong because they form long complex molecules that resist breaking and grab onto any microscope roughness in the surfaces they touch. One of the parts is the resin and the other is the hardener.
Super glue is nothing more than the same type of two-part adhesive, only in its case the hardener is water. Even apparently dry surfaces have microscopic droplets of water adhering to them. When super glue comes in contact with these droplets they create the chemical reaction that causes the super glue to harden.
With this in mind, super glue should work best in humid areas and less well in very dry desert locations. Also, a wipe of both surfaces with a very slightly damp cloth may speed the adhesive's setting. Another idea would be to "huff" on the pieces as if they were a mirror you wanted to fog. This also explains why putting extra super glue on a surface doesn't help. Until it can absorb enough water vapor from the air it'll never harden. In fact, as it starts to harden the surface of the exposed blob of super glue will form a shell that inhibits water vapor from penetrating deeper so the hardening process will grind to a stop.
Why does super glue stick so well to skin? First, under a microscope skin is an adhesive's dream. It's full of large, medium, small and microscopic grooves and pores that provide the perfect type of roughness for glues to grab. Second, the tissues are saturated with water so the super glue can soak in as deep as it wants and still find water to cause the hardening reaction.
The super glue that doctors use is different than the type available in hardware stores. Surgical super glue contains types of alcohols that are less toxic to human tissue. The type sold in stores use ethyl of methyl alcohols that can kill cells.
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