Not long ago I was at a local establishment and people I didn’t know too well were complaining about clothes not treated with dryer sheets. I had to burst out and be a Chemistry Downer by saying, “Dryer sheets just cover your clothes in fat.”

That was the simplest way to put how dryer sheets work. But it wasn’t entirely true. They are much more complex than just fat for your fabrics. They contain clay and scent in addition to fat and are a marvel of consumer chemistry. And they vary in the the form of fat they deliver. Clean Day sheets are a mixture of vegetable fats and other materials, Snuggle sheets are made from stearic acid, while Bounce softer sheets have a modified charged versions of fats. 

To consider how dryer sheets work and why they didn’t come about until the 70s, let’s review the chemistry of washing things.

You might think that science is all about opposite attracting but in chemistry “like dissolves like” is an important concept. Salts and minerals will dissolve in water easily but oily substances  will avoid water. You have to trick them into dissolving so that they can be washed away. This means that detergents contain tails of fats which dissolve grease with a charged head that pulls the grease into water. They work well but can leave a charge on your clothes that makes them feel less soft than they could feel. Fabric softener was developed to counteract that charge. However, modern detergents contain a whole lot more than just this simple surfactant. Some even leave a film of stain resisting polymer that also keeps soap from sticking on your clothes. Laundry detergents have become so innovative that I don’t see a need to use more product on them.

Dryer sheets work by taking away static charge, coating your clothes and making them slippery–this is what we humans consider soft. According to the American Chemical Society,”During tumble drying, the coating containing the softener melts and the compounds get transferred onto the fabrics being dried. The newly attached fatty chains give the fabric’s surface a slippery feel, which people interpret as softness. The compounds also help dissipate static charge by lubricating and increasing the surface conductivity of the fabric fibers.”

Some people have adverse reactions to dryer sheet vapors. Indeed, the familiar scent can carry volatile organic compounds–some of which irritate and others are possibly carcinogenic. The chemicals released are sometimes different than those found on the label, indicating that a chemical reaction occurs during the dryer sheet action.

Dryer sheets can cause clothing to be more flammable and they can leave a residue in the dryer. They can also leave spots on clothes if you overload your dryer.

It goes without saying that fabrics meant to wick away moisture such as athletic clothes will not be effective if they are treated with softners or dryer sheets because they will become coated.

Some laundry enthusiasts say that a ball of aluminum foil works in the dryer as well as dryer sheets. Others say that these can catch delicate clothing and to use tennis balls.

How do I feel about dryer sheets? Personally, I don’t see them as dangerous. It’s more that I find them wasteful and the scent cheap. Their fabric is plastic and do we need any more toss away plastic in this world? Dryer sheet sales account for hundred of millions of dollars per year in the US. Is this worth the cost? I once had a European tell me that the US smells like a combination of dryer sheets and cheese. That’s how prevalent dryer sheets are here. If you want to smell like an American, use dryer sheets.

Do you need to have softer, smoother clothes? How important is it? Believe it or not, looking as if you are too busy to iron is trendy. I have a lot of respect for the US companies that make these sheets. However, I don’t feel any urge to soften my clothes or give them additional scent. I line dry when I can and if clothes are wrinkly or scratchy, I steam them. That’s my chemist’s take on dryer sheets.