Scientific decorations for kids
How many colors are in one felt-tip pen?
Uncover a felt-tip pen’s composition in just a few minutes.
Warning! Only under adult supervision.
- cup of water;
- dental cotton roll;
- dark green/dark red/black felt-tip pens;
- filter paper;
Draw a small circle in the center of a disk of filter paper with a green felt pen. Soak a dental cotton roll in a cup of water and place it in the middle of the green circle – over the course of a few minutes, an elegant pattern of several colors emerges. Optionally, you can trim this filter paper into the shape of a light bulb containing the resulting pattern and draw a base on it with a pencil. You can string a set of such “bulbs” and make your own creative holiday lights! If you alternate with using dark red or black felt pens, your string of festive lights will be multicolored!
As it turns out, a dark green felt pen (just like dark red or black) is composed of several colored compounds that combine to produce dark green. The molecules of these substances have different chemical natures and, as a result, interact with paper in different ways: some of them move through paper more quickly, and some more slowly. We can observe this using the capillary effect: the water we add moves evenly through the filter paper, carrying the dyes with it. This separation technique is called paper chromatography. However, the composition of these felt-tip pens can vary depending on the manufacturer – if the experiment doesn’t work with one particular dark green marker, try another one!
A similar experiment is included in the MEL Chemistry subscription!