You can take this project in many different directions, which is what science is all about! Chances are, you already have all the supplies you need for this project in your kitchen: coffee filters or paper towels, magic markers, and water.
Fill the bottom of a bowl or glass with a little water. Then, cut paper towels or coffee filters into long strips. Draw a large dot of color (black works best) about an inch from the bottom of the strip of paper. Place the bottom of the paper, below the dot, into the water. Once the water starts moving, the paper will stick to the side. You can hook it over the top of the glass, like we did.
The water will be wicked up the paper and through the dot, dissolving and taking some of the dye up the strip with it. You’ll be able to see colors separate as the dyes travel up the strip. It’s fun to see what colors make up different black inks. My kids tried it with colors other than black too. They even made dots comprised of several different colors and watched them separate in the water. Another variation is to put ink on a large piece of paper, drip water on it from a dropper or straw and watch the color travel out in a circle!
We taped some of the strips into our science notebooks. They’re very colorful. Older kids might enjoy trying a 10:1 mix of window cleaner and vinegar to separate the colors.
When you separate the colors from one another on the paper, you’re doing chromatography!
When paper is dipped in water, water molecules make it wet. The water molecules travel up the paper towel. When the water reaches the ink, it dissolves some of the dyes in the ink, and the dyes travel up the paper towel with the water. Some of the molecules that make up the dye are smaller and travel up the paper towel faster than the larger ones, so you can see some of the different colors that make up the ink separate from one another. The number of spots of color you see can tell you how many chemicals make up the color in your marker.
Most importantly, have fun!