eli5: why does supergluing 2 metal pieces take minutes but only a millisecond for my fingers.
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Heat *will* accelerate that reaction, but I suspect moisture in and on skin is a bigger factor. Cyanoacrylate cure is initiated by water, and there’s a lot more water in your skin than in a piece of metal.
doesn’t super glue react quicker in heat?
Moisture. It’s sucking the perfect amount of moisture out of your skin to accelerate the process. It’s impossible to get the perfect amount of moisture from metal.
Superglue is a brand name of [cyanoacrylate](https://en.wikipedia.org/wiki/Cyanoacrylate) or CA glue, and it is a liquid that becomes a hard plastic when it gets wet. Two pieces of metal are not partially made of water like two pieces of skin are, so the only thing turning the CA hard is the humidity. That takes a lot longer, doesn’t penetrate as far, and the surface area isn’t as large (which is the second biggest thing after moisture content that quickens the process, which is why dots of CA glue is better than a single blob).
Superglue dries with water. It sucks the water right out of your skin to dry. Works similarly with anything that contains a lot of water.
Super glue is generally activated by moisture. Your fingers have a lot of moisture in them, while metal doesn’t.
As others have said, Superglue is designed to work with moisture, and your fingers have moisture on and in the skin while metal does not.
Fun trivia, Superglue was actually used as a medical adhesive during the vietnam war to seal up gunshot wounds. This is specifically because of how good it is at sticking skin together.
On top of that, your skin is full of tiny pores and has a huge amount of surface-area for the glue to get into and stick to. Metal tends to be smooth, so has a lot less surface to glue, which produces a more brittle connection.
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