Water Repellency
Water Repellency is how well a surface makes water slide off instead of soaking in.
A waxed baking sheet shows water repellency well. Water drops sit on top as small beads. They roll off the surface without soaking in. An unwaxed sheet soaks the water up instead.
Explaining water repellency by grade level
When rain hits a car window treated with a coating, the drops roll right off. The coating makes the glass so smooth that water cannot grab on. On a plain window, drops stick and sit there. The coating pushes water away before it can spread out.
Projects that explore water repellency
Water repellency depends on how a surface coating forces water to slide off instead of soaking in. You can measure this by timing how long a water droplet takes to travel a set distance down a treated surface. A coating that moves water faster across tilted glass shows stronger repellency.
Different materials resist water in different ways. Some fabrics let water soak in easily, while others make it slide off. Adding a water-repelling spray changes how much water a fabric absorbs, showing that surface treatment controls repellency.