Why does glue not stick to the inside of a package?

You will find Intercol's glue everywhere, such as on all kinds of boxes in the supermarket, from candy to toilet paper and books.

You can stick all kinds of things together with glue, but why never put flat glue on the inside of such a tube?

That is why the Klokhuis made a report at Intercol in Ede, the largest factory of water-based adhesives in the Netherlands.

At Intercol, a thousand different types of glue are made, such as:

• summer glue, for example, construction users in the summer of course
• thick glue you can easily cover books with it
• thin glue for wood
• all kinds of different line are on the back of the shelf here

What's in glue?

every substance consists of molecules of glue, they are actually long chains of glue molecules and they stick together.

These glue molecules are dissolved in water and the moment you start gluing something, the water pulls into the paper, leaving the glue behind and something sticks

We show this here, for example, by applying a little glue to a toilet paper.

With other paper and cardboard exactly the same happens, it just takes longer than with toilet paper.

So that means the toilet paper dries you faster and sticks faster

Most glue tubes are made of plastic or aluminum, this is cut open for demonstration. If you put a little glue on them, you will see that the water is not absorbed and the glue does not dry. The packaging ensures that the glue remains dissolved in the water and therefore does not stick

So that's why glue doesn't stick to the inside of a tube, but then the cap has to be on!

For making glue recipes you need at least these four ingredients

• water (to dissolve in)
• preservative (so it doesn't go bad)
• anti-foam (then it won't foam)
• glue (of course..)