How Does Glue Bond?

Introduction

When a person thinks of glue, we think of the white pasty mess that we used in grade school during arts and crafts. We would place the glue on an item and stick to another. The glue would dry and the pieces would be fixed together. But just how were they able to stay together? What was keeping those two pieces in place? Glue develops a bond between the surfaces. Little did we know, but at the time we were seeing science at its best.

What Is Glue?

Glue is known as an adhesive. This is a substance that can hold two or more things together.  Some glues can withstand water, humidity or even work on uneven surfaces. Glues can be natural or come from a manmade substance such as cellulose or starches. Other types can be made of natural material, such as rubber cement, and some glues are still made from horses. The very first glues ever invented were from tar and beeswax.  

Many Different Types of Glue

There are many kinds of glue. None of them work exactly alike. Some will bond to a surface, dry and hold the surfaces together. Others have to have a chemical reaction occur with the glue and the surface you are putting your glue on. There are others that have to have a reaction to two completely separate components within the glue in order to work. Adhesives are very complicated to understand because each one has a certain special job. The average everyday glue and how it bonds is easy to explain and understand, and therefore will give you a better understanding of how glue does bond.  

How Glue Bonds

As it was stated earlier, glue is an adhesive. The purpose of adhesives is to hold two things together. The glue will settle into the material's pores; this is called cohesion. Cohesion means it can stick to itself. When this happens, it can bond to the surface and this is called adhesion. Adhesion means it can stick to the material you put it on. Then it will dry, the materials are held together by the glue's strength as well as  the material's strength.  Glue can form this hold in the instant it hits the surface. Adhesives are strong enough in some cases that it can hold stronger or just as strong as bolts. There is no definitive theory on what happens when you stick two things together with an adhesive, given the fact that there is a wide variety of adhesives to choose from. All that scientist can agree upon is it does happen and it might possibly happen at a molecular level. Also, glue really has nothing to do with the bonding, rather the chemicals reacting. 
 

How Does the Glue Work

The forces that cause glue to bond to surfaces only occurs when the molecules have a positive end and a negative end. The positive end will attract a negative end from another molecule. In order for the forces to work, the surfaces must be in close contact or joined together. The molecules will then react to each other very strongly. The adhesive must be able to make the surface wet--this helps spread the adhesive and allow as much contact to the area as it can.