SIMPLE SCIENCE

Milk Art

Turn white milk into a colourful work of art

Cotton swab

WHAT YOU DO

1. Pour enough milk into the plate to completely cover the bottom. Be careful not to move the bowl, you want the milk as still as possible.
2. Place a few drops of food colouring on the milk in different spots. Be creative! This is your chance to create real art.
3. Dip the cotton swab in dish detergent.
4. Ready? Set? Go! Put just a tiny amount of soap on the end of the cotton swab, and touch it to the surface of the milk. Then just sit back and watch the magic.
5. WOW! The food colouring will start to swirl and move in different directions, and the once-white milk will become a magnificent, colourful artwork. Cool!

WHAT HAPPENED?
Milk is mostly water but it also contains vitamins, minerals, proteins and tiny droplets of fat suspended in solution. Fats and proteins are sensitive to changes in the surrounding solution (the milk).
When you add soap, the weak chemical bonds that hold the proteins in solution are altered. It becomes a free-for-all! The molecules of protein and fat bend, roll, twist, and contort in all directions. The food coloring molecules are bumped and shoved everywhere, providing an easy way to observe all the invisible activity.
At the same time, soap molecules combine to form a micelle or cluster of soap molecules. These micelles distribute the fat in the milk. This rapidly mixing fat and soap causes swirling and churning where a micelle meets a fat droplet. When the micelles and fat droplets have dispersed throughout the milk the motion stops, but not until after you've enjoyed the show!
There's another reason the colors explode the way they do. Since milk is mostly water, it has surface tension like water. The drops of food colouring floating on the surface tend to stay put. Liquid soap wrecks the surface tension by breaking the cohesive bonds between water molecules and allowing the colors to zing throughout the milk, resulting in a cool, colourful pattern.
So you see, it's not magic… it's chemistry!