Can you keep paper dry in water? Most of us probably did this experiment when we were kids and I knew my science and magic loving kids would love this water project. The idea is simple, keep a piece of paper towel or paper dry in water. Is it possible? Absolutely, if you use the right science.
For this activity all you need is a deep container filled with water, a cup or container that can be submerged completely in the water, and some paper or paper towel. Oh, and a steady hand!
We have done this experiment a number of times with different containers and different bowls. To get the nice pictures my bowl is a bit shorter than the glass, but trust me this does work even if you completely submerge the glass (you could even test this in the bath tub!).
Now stuff some paper or paper towel into the bottom of the glass. It needs to wedge in there enough that it won’t fall out.
This next step is where you need a steady hand.
Flip the glass upside-down and carefully place it into the water keeping it perfectly straight. If you go even a little crooked you will see bubbles which is a bad sign!
Completely submerge your glass, then carefully pull it straight back up.
Check your paper! If you kept it completely straight, your paper will be completely dry. For our pictures we dyed our water green so you can easily see that it never touched our water paper. It’s science magic!
Next, try putting the glass into the water but tip it slightly so you see bubbles, this is the air escaping and letting water in.
Now when you pull out the glass your paper will be wet. See the green water on our paper? That’s from just letting a few bubbles into our glass.
So what is happening here?
Air takes up space and when you submerge the glass in the water the air becomes trapped by the water pressing up from below, and the glass on all other sides. Air is lighter than water so it needs to stay on top of the water. As long as the air can’t escape, water can’t get in and your paper stays dry. As soon as you provide a way for the air to escape by tipping the glass and letting those air bubbles escape, then water rushes in and takes the place of the air and your paper gets wet.