A Milky Way to Paint
Question: Can you make colorful art in a pan of milk?
KIDS’ LAB LESSONS
Many painters use a palette to keep their colors. A palette allows them to have all their various colors available for use, but kept separate so they don't mix. You can make a paint palette of your own by using whole milk and food coloring. But watch out—if you add liquid detergent to the mix, a mix is exactly what you get. Once you see how the mixing occurs, you can begin to experiment with different colors in different patterns to produce new “paintings.”
Whole milk contains milk fat. This fat is usually homogenized, or spread evenly throughout the milk. When you add the drops of food coloring, which is mostly water, the colors sit in the milk in small pools. They do not mix. However, when you add liquid soap, the magic starts. As the soap spreads, its particles mix with the milk's fat particles. As this occurs, the fat begins to move around with the soap. This in turn moves the food coloring around as well. As the food coloring mixes with the white milk, your color palette will slowly turn into a painting of swirled colors.
1 cup homogenized whole milk
Dinner or pie plate or shallow pan
Food coloring of various colors
Liquid dish soap
1. Pour the milk into the plate or pan so that it is about ½ inch deep.
2. Pour 2–3 drops of food coloring in various places around the plate. Be sure to use a variety of colors in order to produce a more interesting mix.
3. Add one tablespoon of dish soap to the middle of the plate.
4. Wait and watch what happens!
Questions for the Scientist
1. Why do you think the food coloring stays where it is (doesn't mix with the milk) when you first add it?
2. Why do you think the soap mixes with the milk?
3. Describe the pattern of colors that formed when you added the dish soap.
4. After a certain period of time, the colors stop swirling and mixing. What makes them stop?
Try this experiment again using different combinations of colors. You can even hold a contest with your friends to see who can produce the most impressive works of art. Also try using different quantities of food coloring. Try to determine whether using more or less coloring produces a better work of art.
You might also try using different kinds of milk, including 2%, nonfat, buttermilk, chocolate or strawberry milk, and cream. Does the fat content really make a difference in the swirling effect of the colors? Are the results different if you change the color of the milk?