I saw this idea on Photojojo a couple of days ago and immediately thought of doing this with Adia, who is very good at math and science. When I suggested this fun experiment for today, she was all over it! She remembered seeing the project on a website she called “Science Steve.” Here is an excerpt from Steve’s post about this Color Changing Milk:
The secret of the bursting colors is the chemistry of that tiny drop of soap. Dish soap, because of its bipolar characteristics (nonpolar on one end and polar on the other), weakens the chemical bonds that hold the proteins and fats in solution. The soap’s polar, or hydrophilic (water-loving), end dissolves in water, and its hydrophobic (water-fearing) end attaches to a fat globule in the milk. This is when the fun begins.
The molecules of fat bend, roll, twist, and contort in all directions as the soap molecules race around to join up with the fat molecules. During all of this fat molecule gymnastics, the food coloring molecules are bumped and shoved everywhere, providing an easy way to observe all the invisible activity. As the soap becomes evenly mixed with the milk, the action slows down and eventually stops.
Steve’s description of this experiment explains that it’s important not to stir the colors and the milk with the cotton swabs, but Adia couldn’t stop herself. She seemed much more interested in seeing what would happen when you stir all the colors together (you get a grayish tan color that looks totally unappetizing!)
I convinced Adia to let me to take photos along the way, before the colors were all mashed together. Aren’t these cool? The blue one looks a little like an angry face.
What You Will Need
- Whole or 2% milk (must have some fat for the science to work)
- Dinner Plate
- Food coloring (red, blue, green, yellow. We also used Neon colors)
- Dish-washing soap (We used Ivory Liquid, but some sites say Dawn works best)
- Q-tips (cotton swabs)
How to Make your Milk Swirl Paintings
Photojojo has a very clear, short video showing how to do this science/art project
Steve Spangler’s Science Experiment, Color Changing Milk. He even has a section on tips to turn this fun activity into a science fair experiment.
Here is a detailed description with great progress photos, of Steve’s color-changing-milk experiment.