Why doesn’t glue stick to the inside of the tube?
Did you know that glue is made up of a substance that sticks to things and a solvent that keeps it liquid until you want it to stick?
According to www.funtrivia.com, when you put glue on a piece of paper, the solvent gradually evaporates until the glue becomes sticky. When the glue is in a bottle or container, there is a space inside the bottle above the liquid that is full of air.
So why doesn’t the glue dry out in the container? Well, there’s a limit to the amount of solvent that can evaporate to fill the space in the bottle. Once the space is full of solvent gas, no more solvent evaporates from the glue and the glue stays runny.
When you squeeze the glue onto paper or other surface, it makes contact with air. So the water molecules start to evaporate and therefore the glue dries and sticks to whatever it is on. As long as the inside of the container remains closed, air can’t get to the glue, so the water molecules stay where they are and continue happily flowing amongst each other.
However, if you leave the bottle unscrewed or entirely open, the air gets to the glue and dries out all of the water molecules and that is when we end up with an almost brand new bottle of glue with a big giant see-through clump inside that just will not come out.
Pic credit: Molly DG
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