Folded or Flat Paper Towel: Which One Absorbs Most?
It’s fall, which means flu season. We all know that washing hands a few extra times a day can help keep colds and flu at bay, so we wash hands frequently and use a paper towel…then another one, maybe even three or four to dry them off. Because who likes to go out with wet hands in cold fall weather, right?
But could there be a way to conserve some of that paper, and get a paper towel to go the extra mile, allowing you to dry your hands with just one single sheet? This activity just might help you find the answer.
This activity is not appropriate for use as a science fair project. Good science fair projects have a stronger focus on controlling variables, taking accurate measurements, and analyzing data. To find a science fair project that is just right for you, browse our library of over 1,200 Science Fair Project Ideas or use the Topic Selection Wizard to get a personalized project recommendation.
To understand how paper towels absorb water, we need to know a little about how they are made.
Paper towels are made of ground up plant material. If you look through a microscope at a torn-up piece of paper (or look up some images on the internet), you will see a web of microscopic plant fibers. Magnifying your paper even more, you would see that the fibers are made of long chains of linked sugar molecules, called cellulose. Water is attracted to cellulose, so water molecules like to be soaked up and stick to the cellulose in paper.
As you looked through your microscope, did you also see the spaces between the fibers? These empty spaces affect the absorbency of the paper: water likes to stick together and fill up these spaces as it follows the water attracted to the cellulose. More spaces allow more water to be absorbed. But what would happen if you add a tiny space between sheets of paper towels? Would the empty space between the sheets help to hold more water?
Extra: If you have more paper towels of the same type, repeat the tests, performing each step in exactly the same way and notice the variations in the outcomes. Does the measured difference in mass vary a lot or just a bit? Is it always the folded or always the unfolded paper towel that weighs more? How about your feeling: do your hands always feel drier when using the folded or the unfolded paper towel? Scientists repeat tests to verify the outcome. Scientists also like to have their studies repeated by a different researcher utilizing a different instrument (like a different scale). If the independent test reveals the same results, the test is called reproducible. Reproducible tests have more scientific value. Can you find a friend to help you make your tests reproducible?
Extra: If you have different types of paper towels available, repeat the tests with them. Do you expect similar results?
Extra: Test other paper products that are used to absorb liquids, like kitchen paper towels, toilet paper, paper napkins or tissues. Do these absorb more water when folded than when used single-layered? Which type of paper product gains most by folding? Can you explain why?
Observations and Results
Did you measure a higher mass for the folded wet paper towel and did your hands feel drier when you used a folded paper towel? This is expected, as the tiny empty space between layers of paper towels helps hold more water.
Paper is made of cellulose, and water molecules like to cling to cellulose. As a result, paper readily absorbs water. Paper towels are especially absorbent. Their cellulose fibers have empty spaces, like tiny air bubbles, between them. Water molecules, which like to stay together, follow the water absorbed by the cellulose and fill up the empty spaces. Layering the paper towel creates more empty spaces for water to fill, which explains why your layered paper towel could hold more water and was more efficient at getting your hands dry.
The next time you reach for the paper towels, remember to fold! You might feel good knowing you just saved an extra paper towel from being used without sacrificing comfort!
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Sabine De Brabandere, PhD, Science Buddies
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Absorption, paper, adhesion, cohesion
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