This is a fun little experiment that you can try with dry erase markers.
Materials
- Dry erase markers
- Plate or container with a smooth, nonporous surface
- Water
Notes: Using a dry-erase marker on porous materials such as fabric will leave permanent stains that will NOT wash off. Do not use Sharpies® or other permanent markers in this activity. Those inks can only be removed with rubbing alcohol.
Experiment
Draw a figure on the surface of a plate or other nonporous container using a dry erase marker. Slowly pour some water onto the plate but not directly onto the drawing. Gently swirl or rotate the plate until the water eventually reaches the drawing. Observe what happens to the marker image.
What’s happening?
You should see the drawing pull away or release from the container and float on the surface of the water. A dry erase marker contains pigments(s), alcohol to dissolve the pigment, and a “binding agent” consisting of an oily silicone polymer. The alcohol in the marker ink quickly evaporates, leaving behind the oily polymer and the colored pigment. Water does not mix with the oily polymer and thus will not dissolve it.
Also, since the polymer is less dense than water, the marker drawing floats on the water surface. If you try this activity with a permanent marker, the images will not release from any surface into water. The binding agent in permanent markers is an acrylic polymer that is not soluble in water but also does not have the “oily” character that silicone does.
Extension
Try making an alphabet soup and move the letters around to spell different words! Try to pick up your drawing and see what happens. Can you put it back?
References
https://www.scientificamerican.com/article/make-your-drawings-float/
https://www.thebestideasforkids.com/floating-dry-erase-marker-experiment/
To view past “ChemShorts for Kids” activities, go to:
https://chicagoacs.org/ChemShorts
