Is glue a glue

Why doesn't glue stick in the tube?

Most adhesives are liquid and come in tubes or bottles. In liquid form, you can distribute it evenly on all surfaces and then glue a wide variety of materials together.

However, glue does not stick in liquid form. Only when it dries and hardens are the glued materials firmly bonded together. Adhesive hardens when it comes into contact with air. It contains a solvent that evaporates in contact with air. A sealed tube is airtight and keeps glue liquid.

What's behind it ...

Many adhesives are made of polyvinyl acetate, which is a plastic. This is made up of many small particles that are all connected to one another. However, if the particles are hard, they do not adhere to anything.

So you have to put it in a different form. They are mixed with a solvent such as acetone. Acetone dissolves the connections between the individual particles and the plastic becomes liquid.

It stays that way for the time being in an airtight packaging. However, as soon as the adhesive comes into contact with air, the acetone in it gradually evaporates and the particles bond together again.

The less solvent there is in glue, the tougher it is and after a while in the air it becomes hard. This is why you always have to close a tube tightly so that no air can get to the glue and it stays liquid. Ah!