OK so I was supergluing something and got a whole heap spilled on my fingers. And it was REALLY hot. I sort’ve rubbed it into my other fingers, but certainly not enough to heat it up. Yet it really suprised me something at room temperature could heat up that much so quickly. Anyone else experienced this? is there some kind of chemical reaction going on here?
Cyanoacrylate glue curing is a polymerization reaction triggered by the presence of atmospheric water (or other weakly alkaline substances). This reaction is what chemists call exothermic, meaning it releases heat during the process. So, yep, what you experienced is to be expected.
So its reacting to the sweat on my fingers?
Whats stopping it from boiling away inside the tube? (from, eg. humidity)
Well, it doesn’t “boil away.” It would polymerize inside the tube and become useless. As for what keeps it from polymerizing in the tube, presumably safe packing keeping it under anhydrous conditions before you open it and as little exposure as possible once the tube has been opened.
I should note that the water is consumed in the reaction. Any water which gets in when you open the tube is quickly reacted, which is what causes the crusty plug you often have to poke out before you can dispense the glue.