Make it at home: Psychedelic milk

Maila Rible, QMI AGENCY

, Last Updated: 1:29 PM ET

 

Your mother probably told you not to play with your food. She was wrong.

Well, you probably should listen to your mother if you're entertaining clients on a business lunch or trying to impress your fiancée's parents. Unless you're eating with six-year-olds, building a mashed-potato mountain and screaming, "The volcano is erupting!" as you pour red wine down the sides is not going to win you repeat dinner invitations. But there's so much nifty science to be found in the food we eat; it's a shame our innocent explorations end up getting squashed by things like "table manners" and "not being disgusting."

But once in awhile you should unleash the inner chemist bubbling inside you, especially when it's an experiment that won't put anyone off their food.

The supply list for this one is pretty simple: You will need milk, food colouring, dish soap and a plate with a bit of a lip.

Pour the milk onto the plate until the bottom is completely covered, but it's not spilling over the sides. Next add a few drops of some different colours of food colouring. Try to keep the food colouring near the center of the plate, only allowing the colours to mix a little bit. Now, add a single drop of dishwashing soap to the center of the plate and watch what happens.

At first you'll see the colours sort of "pushed" to the sides of the plate. But then something strange occurs. The colours swirl and dance in moving patterns. Feel free to play some soothing sitar music in the background to complement the show.

What's going on in the milky miasma on your plate has to do with a number things, including the process that gets your dishes clean.

Let's start with the milk. Milk is made up mainly of water and water has oodles of surface tension. Water molecules will cling to each other for dear life and surface tension is why some bugs can run across ponds and why you can slightly overfill a cup and see that "bubble" of water at the rim. But milk has other things in it besides water and it's more dense than the food colouring. So when you drop in the pretty colours, they float on top.

The soap contains something known as "surfactants." These surfactants lower the surface tension of water, allowing things to more easily mix together and setting the food colouring free to roam about the milk.

But the soap does even more. Along with all that water, milk contains proteins, minerals, vitamins and fat. Just like a kid on the hunt for candy, part of the soap molecule wants that fat and will stop at nothing to link up with it. As the molecules zip around in the milk, rolling and twisting as they join together, the food colouring gets pushed around in the current created by the soapy fat square dance.

Eventually the mixing is complete and the action stops. You can try adding another drop of soap to see if there are any wallflower fat molecules left, but eventually you'll have to start over with a new supply of milk. At least with all that dish soap in there, you've got a head start on post-experiment cleanup.

 


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