What Makes Slime So Strange?

And why is it so fun to play with?

Slime is really weird and really fun at the same time. We love to pull, squish, squeeze, stretch and shape slime because it doesn’t act like other substances. Slime’s odd character can be explained in part by learning about non-Newtonian fluids and viscosity. Understanding these principles helps STEM Club scientists explain what they observe when playing with slime and can inspire new experiments!

Slime can feel like a solid or liquid, because it’s a non-Newtonian fluid.

Slime can feel like a solid or liquid, because it’s a non-Newtonian fluid.

What is Non-Newtonian, Anyway?

The Newton in Newtonian is none other than Sir Isaac Newton, the famed English scientist responsible for numerous scientific and mathematic advances in the 17th century. Newton spent a lifetime questioning and trying to explain the world — he would have been a great STEM Club scientist! Many know Newton from the story of an apple falling from the tree onto his head, which gave him the inspiration to investigate and explain gravity. He’s also very famous for his three laws of motion.

Isaac Newton introduced the concept of Newtonian fluids. What he noticed is that fluids tend to get thicker or thinner when the temperature changes, affecting how fast or slow the fluids flow.

Or, in more technical terms, the fluid’s viscosity changed.

What is Viscosity?

Think of water and syrup. At room temperature, water has a lower viscosity and flows faster than syrup, which is thicker and has higher viscosity. Both will flow faster when temperature rises, and both will flow slower when cooled.

Non-Newtonian fluids also have changes in viscosity, but not just due to temperature. These fluids change when put under different types of stress.

For example, when you put cream into a kitchen mixer and whip it fast, the cream gets thicker and turns into whipped cream — yum! The stress of the mixing changes cream’s viscosity, even when the temperature stays the same.

How far will your slime stretch? Show us! #brainfueltoys

How far will your slime stretch? Show us! #brainfueltoys

Slime Science: Test and Observe

Slime is non-Newtonian. That means its characteristics will change when put under stress. When squeezed, pressed and squished, slime can feel like a solid. But if you let slime sit undisturbed, it will take the shape of its container, like a typical liquid!

The changing nature of slime can be observed just by playing with it in your hands. It’s also a great opportunity for STEM Club scientists to ask, what if?

  • What if I bunch slime into a ball really fast?

  • What if I stretch slime slowly, as far as my arms can reach?

  • What if I lay slime out on the table, and let it sit for 10 minutes?

These questions and many more like these will keep STEM Club scientists searching for answers, observing, reporting and explaining just like Newton did after the apple fell and bumped his head!


Show us your slime! #brainfueltoys

Exploring the non-Newtonian character of slime is bound to make some memorable experiments, and we’d love to what you come up with! Ask a parent or guardian to post a photo or video of your slime project to Facebook or Instagram using #brainfueltoys. You’ll be automatically entered in a drawing for a free science toy! We may even share your post with the whole STEM Club!