Why is it easier to tear a wet piece of paper than a dry one?

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In summary, it is easier to tear wet paper than dry paper because the water in the paper weakens the cohesive forces between the fibers, making it easier to separate them. In the paper making process, the fibers are compressed and dried, increasing their interfiber surface area adhesion. When water is added to dried paper, it expands and breaks some of this adhesion, resulting in paper that is easier to tear.
  • #1
kishtik
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Why is it easier to tear a wet piece of paper than a dry one?
 
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  • #2
Hmm. My guess is that it is to do with the chemistry of the paper. Perhaps it is in a way water soluble?
 
  • #3
Drying the paper out, was the last step in the paper making process, you are simply going backwards in the final process of solidification, hence it becomes less solid/coherant...
 
  • #4
This is just a guess:

Paper is a conglomerate of fibers. They are held together by friction and some sort of adhesive. When you tear the paper, wet or dry, you are essentially separating the fibers. If the paper is wet, you don't have to overcome the force of the (dried?) adhesive.
 
  • #5
Yes! A friend of mine said that water separated fibres, weakening cohessive forces. Can this be true? I knew nothing about cohessive forces.
 
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  • #6
I didn't think it was a cohesive issue, but I was just guessing anyway.
 
  • #7
In the paper making process the 'stuff' starts out as a "slurry" which is a mixture of wood fibers and water, that is squeezed through rollers as to compress the fibers together, and to assist in pressing out the water. This is repeated till the fibers have been pressed together, interfiber surface area adhesion of the fibers that, dried out, and pressed, increases. Naturally, when you add water, to dried paper, it absorbs the water, expands, and thus breaks some of the interfiber surface area cohesion...the result is paper that is easier to tear...
 

1. Why does water make paper easier to tear?

Water weakens the bonds between the fibers in the paper. These bonds are what give paper its strength, so when they are weakened, it becomes easier to tear.

2. Does the type of paper affect how easy it tears when wet?

Yes, the type of paper can make a difference. Thicker and more absorbent papers, such as paper towels, are easier to tear when wet because they have more space between the fibers for water to penetrate and weaken the bonds.

3. Is it easier to tear a wet piece of paper against or with the grain?

It is easier to tear a wet piece of paper with the grain. The grain is the direction in which the fibers of the paper are aligned. When tearing against the grain, the fibers are more likely to stick together, making it harder to tear.

4. Why does wet paper feel weaker than dry paper?

When paper gets wet, the water fills in the spaces between the fibers. This creates a smooth surface and reduces the friction between the fibers, making the paper feel weaker and easier to tear.

5. Does the temperature of the water affect how easy it is to tear paper?

Yes, the temperature of the water can make a difference. Hot water can break down the bonds between the fibers more quickly, making the paper easier to tear. However, extremely hot water can also weaken the paper too much, causing it to tear too easily.

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