Call it magic milk, milk fireworks, color changing milk, or tie-dye milk. Whatever you name it, give this super easy process science/art activity a try!
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Magic milk is a very popular science and art activity for kids to do. It is simple to set up, yet keeps the kids fascinated as they do it over and over again. Every time we do this demonstration I am impressed with the new variations my kids come up with and the new ways they choose to carry out their ideas. This time they added glitter, mixed colors, and developed interesting shapes and patterns.
Milk (we used whole since that is what we had in the fridge)
A bowl or casserole dish
Glitter (if desired)
Liquid dish soap
- Pour milk in a dish. You don’t want or need much, just a thin film that covers the bottom of the dish.
- Squeeze a few drops of food coloring or liquid water colors into the milk. Add glitter, if desired.
- Dip the end of the toothpick into the dish soap and then into the center of one drop of colored milk. Don’t stir it! Watch the color erupt and scatter like a firework in the sky!
The Science Behind Magic Milk
There are actually a few different things that are going on here. First, dish soap is disrupting the surface tension of the milk. Remember when we did our fun experiment with surface tension to see how many drops of water we could fit on different coins? Remember the cool little dome that water forms at its surface? All liquids, including milk, act this way to some extent. Adding soap interrupts those bonds along the surface, making the surface molecules spread out and the colors explode like fireworks!
Second, soap is super interesting. One end of a soap molecule LOVES water (hydrophilic) while the other side HATES water and loves oil and fat (hydrophobic). Soap can get dishes and clothes clean because the hydrophobic end picks up the grease, oil, and dirt, while the hydrophilic end dissolves in water and washes all the dirty stuff away with it.
Milk, especially whole milk, contains fat and proteins. When soap is added to milk, the hydrophobic end of a soap molecule grabs onto a fat molecule in the milk. With millions of molecules finding a partner all at once, the mixture gets all stirred up! You will notice in my video that it looks like the milk is erupting for several seconds after dish soap is added. This is why. It truly is magic milk!
You can easily turn this activity into an interesting science fair experiment by trying it out in different liquids. What happens when you try skim milk versus whole milk? What about something like cream that has lots more fat in it? What about water? Try vegetable oil? Record your findings and enjoy the process!
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