MaterialsInMotion

My friends and I were working in one of the study rooms in our residence hall when we decided to take a break and start doodling on the room’s whiteboard. After a bit of fooling around with dry erase markers, I grew curious as to how they actually worked. Why was I able to wipe the ink away with my bare hands? What makes them different from wet erase markers, which need a wet paper towel or a special cleaning solution to be erased? I quickly found this YouTube video by George Zaidan from the National Geographic about the science of dry erase markers.

Zaidan highlighted five main ingredients in most dry erase markers: a solvent, a pigment, a resin, a release agent, and a wax. The solvent keeps the other ingredients in solution, the pigment gives the marker its color, the resin evenly distributes the pigment throughout the solvent, the release agent allows the pigment-resin solution to sit on top of whiteboards instead of absorbing into them, and the wax helps to prevent the marker from drying out if left uncapped.

When you write on a whiteboard, the solvent almost instantly evaporates, leaving the pigment-resin solution and the release agent on the whiteboard. These three ingredients are carefully chosen so that the pigment-resin solution doesn’t mix with the release agent and instead sits on top of it while the release agent sits on top of the whiteboard. Thus, when you go to erase your writing, the pigment comes off easily, sometimes leaving behind the release agent if it’s colorless.

This video still leaves me wondering what’s different about wet erase markers, though. I presume that either the solvent doesn’t dissolve or that the release agent and the pigment-resin solution mix together and need a liquid to be removed from the whiteboard. However, these questions will have to be saved for another time.