Milk Swirl Experiment

Milk Swirl Experiment (4)

Here’s a neat STEM experiment that Travis tried once before (aiming to imitate the look of the Northern Lights), but this time we were more focused on the science of surface tension and why the experiment works as it does.

I can’t vouch for every type of non-dairy milk on the market, but the activity works great with oat milk.

To start, simply pour a layer of your milk into a shallow bowl. Add drops of food coloring near the center (just one or two drops of each), close together so they are nearly touching.

Milk Swirl Experiment (1)

Now dip a q-tip swab in a bit of liquid dish soap. Touch lightly to the food coloring…

Milk Swirl Experiment (3)

…and watch the colors skitter away! There is definite wow factor to this one. Here’s a quick clip of our second round (because of course we needed to test it out more than once!).

Travis and I talked about what’s really happening here after all the swirly fun was done: The soap has both a hydrophilic (water-loving) end and a hydrophobic (water-fearing) end. The latter grabs onto the fat in the milk, which means all the milk molecules start to get pulled apart and the colors go skittering along with them.

All that science aside, it’s just so fun to watch! If you use a different type of non-dairy milk, please share your results in the comments!

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