If you have an old, well-used whiteboard in your classroom, you might see something a little strange—ghosts!
Not the spooky kind if you are seeing those, that's up to you.
I'm talking about the ghosts of lectures past—faded words and numbers, or a smudgy stain.
Dry erase markers are designed to write on smooth, hard surfaces and erase without a trace, so how come they're sometimes so hard to erase?
And what can you do to get rid of the leftover marks?
The ingredients of a dry erase marker aren't actually all that different from the ingredients of permanent marker.
Both have three main components: solvents, pigments, and polymers.
The solvent is the liquid that carries all of the other ingredients inside the marker, and after you write something, it evaporates.
Usually, markers use ethanol, which is the kind of alcohol people drink, or isopropanol—aka rubbing alcohol—because they evaporate quickly, which means it's harder to accidentally smudge whatever you've just written.
The pigment of course is the thing that gives the ink its color.
