How Glue Sticks

Glue is an adhesive that sticks things together. When you spread glue between two surfaces, it flows into the tiny bumps and gaps in both surfaces. As the glue hardens, it locks the two surfaces together. Different types of glue work in different ways, but they all create a strong bond.

How Glue Bonds

Even smooth surfaces have tiny bumps and holes when seen under a microscope. Liquid glue flows into these spaces. As the glue dries or hardens, it grips both surfaces from the inside. Some glues work by evaporation, where the liquid dries and the sticky parts remain. Others work through chemical reactions.

Types of Glue

White school glue dries when water in it evaporates. Super glue hardens through a fast chemical reaction when it touches moisture. Epoxy glue uses two chemicals that harden when mixed together. Hot glue melts and then hardens as it cools. Each type of glue works best on certain materials.

Fun Facts

• Super glue was discovered by accident in 1942 when a scientist was trying to make clear plastic gun sights.
• Some glues used on spacecraft can hold in temperatures from minus 423 to 500 degrees Fahrenheit.
• Ancient Egyptians used glue made from animal hides over 3,000 years ago.

Did You Know?

Super glue bonds so quickly because it reacts with the tiny amount of moisture on almost every surface. Even the moisture in your skin can trigger it, which is why super glue can accidentally stick your fingers together!