Why do clothes shrink?

It’s a modern day tragedy: you have a favorite piece of clothing that fits you perfectly, but when it comes out of the wash, it shrunk. What happened? what did you do wrong? Well, lets take a look.

There are two types of shrinkage, relaxation shrinkage and progressive shrinkage.

Relaxation shrinkage, mostly common in cotton, takes place due to the way the fabric is manufactured. During construction of new clothes, tension is applied to cotton yarns. This tension is suddenly released between the fibers when they are exposed to heat, whether they are steamed, washed or dried. As a result, the fabric shrinks to its natural size, which happens to not be the size that you tried on at the store [insert crying face]. This type of shrinkage is common in most cotton fabrics, which is why they are expected to shrink in the very first wash.

The other type of shrinkage, called progressive shrinkage, is common in animal fabrics (hair) such as wool, mohair and cashmere. As the name implies, during progressive shrinkage, the clothing shrinks a little more each time it is thrown in the wash. But why does this happen? Like the hair on our head, these animal hairs have scales on them. So when the wool gets wet and warm, the scales on the side tend to stick out. Then as you agitate these and rub the fibers against each other in the wash, they lock together. As you continue to agitate the fibers, they get stuck together more and more and the fabric continues to get thicker and thicker and shorter and shorter.

Man-made fabrics like polyester, will never shrink. The only reason a synthetic fiber will ever shrink is if there is a blend of natural fibers in the fabric. Here is a good way to look at it, the more natural fibers present, the more likely the clothing article will shrink.

In an attempt to debunk some myths, Whirlpool, an appliances company conducted some tests to determine where in the laundry process shrinking takes place. According to their study, it is the hot water from the washer that causes the most shrinking, and not the action of the dryer. In addition, the study found that some shrinking takes place in the dryer not because of the heat of the dryer, but because of the spinning action of the dryer.

What do you think? Do you like this? How about a question for next week’s blog.

Sources used-

http://www.ehow.com/info_8568102_clothes-shrink-dryer.html

http://www.ehow.com/about_6360634_clothes-shrink-washer-dryer_.html

http://www.npr.org/templates/story/story.php?storyId=98759520

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How Is Lightning Generated?

At any one time, there are about 2000 thunderstorms happening all around the world. In one day, about 8 million lightning strikes take place, unleashing the power of more than 2 million tons of TNT!! But how do they form in the first place?

Here it goes:

Clouds are in the first layer of the atmosphere, called the Troposphere. Currents of turbulent wind causes clouds to mix and hit each other. As a result, friction is produced between tiny water and ice particles called “hydrometeors.”

Electrostatic charge begins to build up in these clouds. For unknown reasons, the lighter particles pick up the positive charge and the heavier particles pick up the negative charge. As a result, the top of the clouds become positively charged and the bottom of the clouds become negatively charged.

 We know that opposites attract and insulators inhibit.  As positive and negative charges begin to separate, an electric field begins to generate between the top and bottom of the clouds. Further separation of the positive and negative charges strengthen the electric field.

Since air is a very good insulator that inhibits electric flow, a LARGE amount of charge (measured in millions of Volts) needs to generate before lightning can take place. Once this threshold is reached, the strength of the build-up of charge overcomes the strength of the insulating air, and LIGHTNING STRIKES! BAM

When lightning strikes the ground, the heat from the electricity raises the heat of the surrounding air to 20,000 degrees celsius (three times hotter than the surface of the sun) VERY quickly. As a result, the air is compressed and explodes outward from the channel, forming a shockwave of compressed particles in every direction. The rapidly expanding waves of compressed air create a very loud noise that we call Thunder.

What do you think? Do you like this? How about a question you would like me to answer for next week’s blog.

Sources Used-

http://regentsprep.org/regents/physics/phys03/alightnin/

http://www.thenakedscientists.com/HTML/articles/article/howdothunderstormswork-2/

http://www.srh.noaa.gov/jetstream/lightning/lightning.htm

http://www.loc.gov/rr/scitech/mysteries/thunder.html