It is one of the mysteries of life that has puzzled many people throughout history. The sticky substance we all call glue; it sticks things together, but doesn't stick inside the bottle! Why ????
Is this magic? no!!!! It's science - and it's because of water.
Ordinary white glue is made up of a variety of chemicals called polymers. These polymers are made of long fibers that are either sticky or stretch. White glue also contains water. Water acts like a solvent that keeps the glue wet until you stick it on. When you put glue on a piece of paper, the water evaporates. Water evaporates (from liquid to gas). As the water evaporates, the glue dries and hardens. The only things left are the sticky polymers that hold things together. This process is called mechanical adhesion.
So why doesn't the white glue stick inside the bottle?
When the white glue is inside the bottle, there is not enough air inside the bottle to make the water sticky as the water evaporates. Basically, the bottle protects the glue from air and keeps the glue wet. If you have left the top of the glue bottle open for a while, you may have noticed that the glue has dried!
What is Super Glue? You may have noticed that super glue dries faster than white glue. Super glue works differently than white glue. Instead of a polymer in white glue, super glue is made from a chemical called cyanoacrylate. When it chemically reacts with water vapor in the air, it binds the chemicals together. This process is called chemical adhesion.
No matter how dry the air is, there is always water vapor in the air. The super glue should be tightly sealed to prevent the water vapor from penetrating and the chemical reaction with the glue to prevent it from drying out. So whether you are talking about white glue or super glue Water is the element. With white glue, you will need bottled water to prevent it from drying out and sticking.