Grades 3–5 · Everyday Life
Why can a whiteboard mark wipe away?
A whiteboard marker leaves a wet colored line. Its ink contains small colored particles and ingredients that help the ink flow. As the liquid carrier leaves, colored material remains at the surface of the board.
In the diagramDry-erase color can lift off a smooth boardThe colored material moves to the eraserNonporous boardDry color rests at the surfaceEraserColor collectedA release ingredient helps prevent strong sticking to the board.
Dry-erase ink also contains release ingredients. These help keep its color from sticking strongly to the board. The board has a smooth, nonporous surface, so the colored particles remain accessible instead of sinking deeply between paper or cloth fibers.
When an eraser moves over the dry line, it loosens and collects colored material. The board looks lighter because much of the color has moved away. Some colored material can remain as tiny traces after much of the line has been removed.
This change is a movement of matter. The ink has not become invisible because it was heated. The kind of ink and the kind of surface work together to make the line easy to remove.
About this explanation
Starting knowledge: Know that ink contains colored material and that surfaces can be smooth or porous.
Sources
- EXPO — Frequently Asked Questions: Dry-erase ink and release agents