Laundry science

Have you ever wondered how dryer sheets work?

I have. I tend to collect static electricity - my hair, my clothes, even my cats. So I absolutely have to have a dryer sheet in the dryer whenever I’m doing a load of laundry. If I don’t, I’m doomed to be a crackling, zapping, static-y mess. So in goes a dryer sheet, and out comes nice, static-free laundry. It’s like magic!

Well, actually, it isn't magic, it's science. Here’s how they work.

First, let’s talk about static electricity. Static electricity occurs when an electrical charge builds up on a surface. Electrical charge is made of electrons. (“Electrons” and “electricity” sound so similar because they are from the same root.) What are electrons? They are one of three major particles that make up atoms, along with protons and neutrons. The names of these things refer to the electrical charge that they carry: neutrons are neutral – not charged; protons have a positive charge; electrons have a negative charge. So when the negatively charged electrons flow in a stream – that’s considered an electric current. Or when electrons build up on an unmoving surface – that’s considered static electricity. (It’s called “static” because it doesn’t move.)

One other important thing to know about protons and electrons is that they are attracted to each other. When an atom has equal numbers of electrons and protons, all of the positive charges and negative charges cancel each other out, leaving the overall charge neutral. If an atom has more electrons than protons, it is negatively charged, and, of course, if there are more protons than electrons, it is positively charged. Neither of those situations is very stable – atoms like to be neutral. So a negatively charged atom will try to find a positively charged atom and stick to it.

So if atoms like to have their protons and electrons balanced out, how do you get a buildup of electrons on a surface to make static electricity? When clothes are tumbling in a dryer, they are rubbing together like crazy in a warm, dry environment. This heat and friction makes the charges on the surface of the clothes separate. Take a look at this diagram, which shows the separation of charge on a sock. Some socks will get extra electrons, and other socks will lose their electrons. This is an unstable situation for the socks. The atoms want to regain their neutral charge. So as the socks are tumbling in the dryer, a sock with a negative charge will find another sock with a positive charge and stick to it. Now when you pull the socks out of the dryer, they will remain stuck. It doesn’t have to be socks, of course. It could be sleeves of the same shirt, folds of a skirt, shirts to each other, underwear to pants. They will stick together. Voila. Static Cling.So let’s go back to dryer sheets. Dryer sheets reduce this buildup of static electricity by releasing extra protons into the dryer during the dry cycle. These extra protons stick to the negatively charged clothes that are building up. And because these negatively charged clothes are now balanced with extra protons, they no longer stick to other pieces of clothing. So you get a nice, non-sticky load of warm, dry clothes at the end of the cycle.

This is a perfect illustration of how science can be found everywhere you look – even in something as mundane as doing the laundry. And I think we should all give a big hand to the science of static electricity – and those who figured out a way eliminate it.