What makes slime stretchy?

When you first mix the guar gum with water, it doesn't become slime straight away.

Instead, the guar gum absorbs water and forms millions of long, tangled chains called polymers. At this stage, the mixture is thick, but the chains can still slide past each other quite easily.

Something else is needed before it becomes stretchy slime.

What does the borax do?

The borax solution acts like tiny bridges between the polymer chains.

Instead of sliding around independently, many of the chains become linked together to form one giant network.

The more connections that form, the more the slime behaves like a stretchy solid instead of a runny liquid.

That's why even a small change in the amount of borax can completely change how your slime feels.

Why did your slime change?

During your investigation, you changed one variable at a time.

Perhaps you added more borax.

Perhaps you used less guar gum.

Every change affected how many polymer chains could link together, changing the slime's strength, stretchiness and stickiness.

This is exactly how scientists develop new materials—they test one change at a time and compare the results.

Curiosity Spark

Scientists don't just make slime for fun.

Materials that behave like slime are used to make contact lenses, wound dressings, medical gels, sports equipment, and even soft robots.

If changing just one ingredient made such a big difference to your slime...

What do you think scientists could invent by changing hundreds of different ingredients?

Try These Next

 [Sick Shampoo Slime] – Does changing the shampoo change the slime?

[Snail Slime] – Make an amazing stretchy gel inspired by real snail mucus.

 [Invisible Cushion] – Another investigation where changing just one variable completely changes the result.