What you'll need:

• 4 different brands of paper towels
• a jar of quarters (or other coins, but they all must be the same - for instance, all pennies or all quarters)
• bowl of water
• teaspoon
• medicine or eye dropper
• two friends or family members
• record sheet & pencil (see below)

In research laboratories, papermakers test the paper they make for physical properties such as strength, absorbency, stretch, tear resistance, folding endurance, and stiffness. They also test for optical properties like transparency, opacity, brightness, color, and gloss.

Although you may not think about it, you perform these same kinds of tests when using and buying paper products. For instance, did you ever wonder which brand of paper towel is the strongest or most absorbent? The following two experiments can help you test paper towels for these two properties: wet strength and absorbency.

Testing Wet Strength

Wet strength is the strength of paper when it is wet. It can be measured by the amount of weight that a wet paper towel can support.

1. First, design a sheet to record your data. Here's an example:
 

3. Next, tear or cut equal pieces from each brand. Your four sheets must be exactly the same size. (Note: because all perforated sheets of paper towels are not equal, be sure to measure each sheet. Trim off excess if necessary.)

4. Ask your two friends or family members to hold the Brand A paper towel at each of the four corners over the sink or a container.

5. Next, pour 5 teaspoons of water onto the middle of the paper towel.
 

6. One by one, carefully place the coins onto the wet area of the paper towel. How many coins will the paper towel hold before tearing? Record your results. 7. Repeat with the other three brands. Record your results.

Now rate the four brands of paper towels according to the number of coins they held, with the brand holding the most number of coins receiving a rating of 1, and the one holding the least number of coins a rating of 4. Which brand was strongest? Which was weakest?

Absorbency can be measured by the amount of liquid a paper towel will hold.

1. First, design a sheet to record your data. Here's an example:

3. Next, cut equal pieces from each brand. Your four sheets must be exactly the same size. (Note: because all perforated sheets of paper towels are not equal, be sure to measure each sheet. Trim off excess if necessary.)

4. Fill the medicine or eye dropper with water. Ask two friends or family members to hold the Brand A paper towel at each of the four corners over the sink or a container. Now squeeze one drop of water at a time onto the paper towel. Count the number of drops the paper towel would absorb before starting to drip. You may have to fill the dropper several times. Record your results.

6. Now rate the four brands of paper towels according to the number of drops they held without dripping. The brand holding the most number of drops will receive a rating of 1, and the one holding the least number of drops will receive a rating of 4. Which brand was the most absorbent? Which was the least absorbent?

Adapted from Paper Towel Testing;
Lawrence Hall of Science, University of California at Berkeley.