Today’s Wonder of the Day was inspired by Taryn. Taryn Wonders, “why does paper rip easily when wet” Thanks for WONDERing with us, Taryn!
Do you love creating your own unique, original works of art? Some kids love to draw or paint pictures. Others might prefer to sculpt something out of clay or fold paper into intricate origami animals.
If you enjoy making three-dimensional works of art, then you might have enjoyed creating a papier-mâché project in the past. Who wouldn't have fun dipping strips of paper into a glue-like solution before pasting them onto an object or a mold?
Of course, the best part of papier-mâché projects for some kids is creating the strips of paper in the first place. Many papier-mâché projects use strips of newspaper, so the first step is often to get a pile of newspapers and tear them into hundreds of smaller strips to use later.
Tearing newspaper isn't too difficult, since it's relatively thin. If you've ever torn construction paper before, you know it's thicker and harder to tear. If you put several sheets of notebook paper together and try to tear them, you'll see that the thicker the stack gets, the harder it is to tear.
Sometimes when you're in the middle of a papier-mâché project, you might dip a strip of paper into the glue-like solution and then realize that you need a smaller or thinner strip of paper. No worries! All you need to do is rip the paper into a smaller, thinner piece.
When you go to do that, you might notice something interesting: when the paper is wet, it tears very easily. In fact, it may be so wet that it almost falls apart in your hands. What's going on here? Why does the water make the paper easier to tear?
You may already know that paper is made from trees, so a typical piece of paper is composed mostly of cellulose (wood) fibers. These fibers are stiffened and held together by strong hydrogen bonds between the cellulose fibers.
When paper gets wet, however, those strong hydrogen bonds between cellulose fibers get broken down and the fibers separate more easily. This happens because water is made up of hydrogen and oxygen. As a result, its molecules tend to form hydrogen bonds with the hydroxyl (hydrogen and oxygen) groups in the cellulose fibers.
When the hydrogen bonds that hold the cellulose fibers together break apart and weaken, this causes the fibers to separate more easily. Thus, the paper becomes weak and much easier to tear. Even thick stacks of notebook paper can be torn easily when they're soaking wet.
You may have also noticed the effect water has on paper if you've ever left a piece of paper in your pocket when your jeans go through the washing machine. When it comes out of the wash, it's probably disintegrated.
If you've ever left paper money in your pocket, though, it tends to fare better than notebook paper. Why is that? Rather than cellulose fibers, paper money is composed mostly of cotton or linen fibers that are not affected by water to the same extent as notebook paper.