Why Doesn’t Super Glue Stick To the Inside of the Tube and How Does Super Glue Use Moisture To Stick To Skin?

Super Glue will not stick to the inside of its tube because the tube contains oxygen in the form of air but excludes water.

Oxygen inhibits whereas water catalyzes.

Super Glue doesn’t stick to the inside of the tube because, being based on a cyano-acrylate monomer, it requires moisture in the form of water or some other active hydrogen-bearing compound to polymerize.

This explains why the best join between two surfaces is made using a thin glue line.

An excess thickness of glue will lead to a retarded cure. This moisture sensitivity explains two things.

First, why the bottle comes with a seal that’s impossible to break without covering oneself in glue and why the resulting spillage adheres so well to your skin, being warm and moist, skin makes an ideal substrate.

The Loctite company in the US discovered the inhibition by oxygen of the otherwise rapid polymerisation of cyanoacrylate.

That is why the bottle must always be left with plenty of air inside.

The liquid monomer converts to solid polymer when oxygen is excluded by trapping it between close-fitting surfaces.