Apple #518: How Dryer Sheets Work

I have a request!  Regular Daily Apple reader Jason wants to know about dryer sheets.  How the heck do those things work, anyway?

Good question.  Dryer sheets coming up.


(Photo from Pinky Has a Brain)

• The first thing to know is that washing and especially drying clothes rubs the clothes together, and at the same time, knocks electrons off of each other.

• If you were to wash and dry your clothes using only detergent and no softeners, by the time you pulled your clothes out of the dryer, they'd be snapping and popping from the static electricity.  A sweater with too few electrons might be stuck to a sock with too many electrons.  Not visible to your eye would be other loose electrons floating around inside the dryer.

• Liquid fabric softeners, first invented in the early 20th century, helped this problem somewhat.  They were supposed to make the fabrics softer to the touch, but since they carried an inherent positive charge, they were also supposed to reduce the amount of negative electrons getting stripped from the clothes.

First there was liquid fabric softener.  Nice idea in theory, but in practice, not too effective and also not that convenient.
(Photo from petwelfare411, which no longer seems to be working)

• However, liquid softeners had to be added during washing (and only after the first wash cycle, so that wasn't convenient).  Since the positively charged softeners were added while the negatively charged detergent was still in the wash with the clothes, most of the time the anti-static benefit of the softener was reduced or even nullified.

• In the 1960s, though, one helpful individual named Conrad J. Gaiser figured out how to put liquid fabric softener onto a small sheet of material and dry it so that it stuck there.  These softener sheets were to be added during drying instead of washing, which was far more helpful.  The heat of the dryer and the moisture coming up off the wet clothes released the dried softener from the dryer sheet and allowed it to work its magic.

Ah, the dryer sheet: fabric softener and static cling eliminator in one.
(Photo from some strange site which I think is manchcommunications.com)

• Most dryer sheets fresh out of the box will feel a little sticky or tacky to the touch.  That means they contain a surfactant.  Surfactants are fatty molecules (I didn't make up that term, I swear) that have two sides.  One side likes to cling to water and the other side likes to cling to fabrics.  

• When the heat of the dryer releases the moisture in the wet clothes, the heat of the dryer also "melts" the waxy surfactant and puts it to work.  The surfactant latches onto some of that moisture in the humid air of the dryer and it latches its other side onto the fabrics.  In this way, it coats the clothes to make them softer and smoother to the touch.  

• The fatty surfactant also has a positive charge, as most fatty things do. The positive charges on the dryer sheet match up with the negatively charged clothes and thus static cling is pretty much eliminated.

• Finally, many dryer sheets also now have various perfumes added to give your clothes a particular scent.  Some people don't like the perfumes or are allergic to them, and there are some dryer sheets available without added fragrance.

• One caveat about dryer sheets is that, over time, those surfactants can build up on your clothes.  That's especially the case with thicker fabrics, such as towels.  If you notice that your towels seem to be less absorbent than they used to or if the pile of the towels stays matted or clumped together even after you've washed them, they've probably got fabric softener build-up.  Here are a couple of tips that can help get rid of the build-up:

• Wash them again in very hot water.  Instead of your regular laundry detergent, use either baking soda, washing soda, or borax.  Rinse twice.  Don't use dryer sheets or fabric softener.

I am a convert to the borax and I am a fan.  It helps keep detergent from building up in the wash and it helps whiten whites and brighten colors.  It works better if you dissolve it in water before adding it to the wash.
(Photo from Passionate Homemaking)

• Using only hot water for a whole load of towels can be a bit pricey, though.  If you want to wash your towels as usual but still get rid of the build-up, first, wash & dry only your towels together.  Since like fabrics don't cling as much to other like fabrics, there won't be much static cling and you may not even notice the absence of the dryer sheets.

• During washing, add about a half cup of vinegar before the second rinse cycle. The vinegar will help get rid of the extra surfactants.  Vinegar also acts as a natural mild fabric softener, so the dryer sheets may not be necessary.

• Wash them this way the next 3 or 4 times and your towels should feel softer and more absorbent again.

• One alternative to dryer sheets is dryer balls.  They're plastic balls with spikes all around them.  They bounce around in the dryer with your clothes, allowing the warm air of the dryer to penetrate the various nooks and crannies of your clothes more easily.  Clothes are said to dry faster, and the bouncing action is said to produce the same softening effect as dryer sheets. 

Any time a product label is sprinkled with exclamation points and wow sunbursts like this, I'm immediately skeptical that the product can do what it exclaims.  In this case, I'd say the dryer balls do about 60% of what they claim.
(Image from Best of As Seen On TV)

• In my experience using dryer balls, they did fluff my clothes a bit and they did reduce drying time somewhat.  But they don't do much about the static build-up, and my clothes didn't feel quite as smooth or have as nice a fragrance using only the balls and no dryer sheets.  So now I use both the dryer balls and the dryer sheets.

Sources
TLC How Stuff Works, How Dryer Sheets Work
Today I Found Out, How Anti-Static Dryer Sheets Work
Indiana Public Media, A Moment of Science, How Do Dryer Sheets Work? 
The Straight Dope, How do dryer antistatic sheets work? 
eHow, How to Soften Bath Towels in the Laundry
About.com, Frugal Living, Dryer Max Dryer Balls: Product Review