Oobleck – What is It and How to Make It?

Science allows us to enjoy all sorts of things. Whether internet technology gives us free access to entertainment on a daily basis, communication or business opportunities, or a refrigerator that keeps our drinks cool and our food from going bad, technology keeps us safe and entertained.

There are fun aspects to science, which when applied in practice, can be entertaining for both adults and children. Such is the Oobleck, something most people have heard of but often have no clue about what it does and how to make it, not to mention how it works. Here is a detailed explanation of what Oobleck is and how to make it.

Oobleck – The Name and What it Is

Oobleck is a name for a non-Newtonian fluid. It comes from a book called Bartholomew and the Oobleck, written by Dr. Seuss, released in 1949. A young man must rescue a kingdom from a sticky green substance called the Oobleck. As one can guess, Oobleck is a non-Newtonian fluid.

Non-Newtonian fluids behave differently than other fluids and are named thusly because they do not follow Newton’s law of viscosity. Namely, they behave differently under slow flow and under high tension. When moved around slowly, they will be liquidy but as soon as they are exposed to high stress, for example, a punch, they will harden immediately. Oobleck is typically used in science demonstrations involving speakers, because of the way it reacts differently to low and high frequencies.

AlejandroLinaresGarcia, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons – cropped

How to Make Oobleck – Starch!

Oobleck is made out of cornstarch, typically. Mixing it with water is enough to make it into a non-Newtonian fluid. Adding food coloring is optional, but it helps if the demonstration is made for children. 

The best way to make Oobleck is to start with water in a bowl, usually a cup of water. Adding starch and mixing it with a spoon or by hand is the way to go. Add the starch slowly after a while, because you do not want to make it a solid, but rather a non-Newtonian liquid. When the mixture of starch and water is right, try punching it and see whether it becomes solid. If it does not, add more starch. After you mix the right amount of starch and water, add coloring to make it even more interesting. 

Why Does This Happen?

Viscosity does little in terms of actually explaining why these liquids behave in the way they do. Continuum mechanics does a better job, using rheometers and measuring strain rate tensors, through extensional flow and oscillatory shear. Dilatant fluids like Oobleck are just one of the many subcategories of non-Newtonian fluids. 

There are other known materials that are non-Newtonian fluids, such as ketchup, nail polish, molasses, various silicone oils, and many more.

Oobleck is a name for a substance made out of water and cornstarch, which is a non-Newtonian fluid, known for its properties of becoming solid under pressure or stress, then reverting back to its liquid state under little or no tension.