Conventional dryers apply heat to wet clothes to evaporate the moisture, or turn the liquid water into a gas. This resultant gas is, of course, steam. So why design a dryer to apply more steam to clothes?
Even though steam is a byproduct of drying, applying steam at the right times to wet clothes or dry clothes has advantages. Steam penetrates and moistens clothes deeply, which has a softening effect that reduces wrinkles. Also, because steam can reach high temperatures, it effectively sanitizes clothes, which helps to eliminate those nasty smells.
Steam can offer similar benefits to completely dry clothes. For instance, if your favorite shirt reeks of that smoky bar you went to last night and you don't have time for a full wash the next morning, you can throw it in an LG steam dryer for a quick 20-minute steaming -- what LG calls the SteamFresh cycle. Without using liquid water or even detergent, the steam alone can refresh the item. But make sure that shirt doesn't have any stains before you drop it in this cycle because the hot steam might set them.
Steam dryers can also reduce the wrinkles in dried clothes. This is especially helpful if you're not around when the dryer cycle ends, and you're clothes have hardened with wrinkles by the time you get to them. Running the dryer again with steam could soften and de-wrinkle them.
Not all steam dryers were created equal. They apply different steam in different ways. Maytag models don't release a stream of pure steam, but rather a fine mist to the clothes. The heat in the dryer then raises the temperature of the mist to turn it to steam. Other dryers use a steam generator to release pure steam to the clothes.
In the steam dryers we've discussed so far, steam doesn't do any drying per se, but rather refreshes and reduces wrinkles. The dryer simply releases steam during the cycle before drying the items again. But as odd as it sounds, steam could potentially dry fabrics, too. An advanced drying technique involves using superheated dry steam, which is steam that doesn't contain any liquid water. This kind of steam is purely gas and invisible to the human eye, as opposed to wet steam, which suspends visible water droplets.
By superheating dry steam to a high enough temperature, machines can use steam to dry items. The very hot steam effectively heats moisture to the evaporation point [source: van Deventer]. Then, the dryer circulates the resulting evaporated moisture out of the system and repeats the process. Though intended for industrial dryers, perhaps the technology of superheated steam dryers will eventually make its way into mass-produced home dryers.
If you crave the benefits of steam drying but can't afford to cough up the money for a new top-of-the-line dryer, there are easy alternatives. For instance, merely hanging a wrinkled shirt in your bathroom while you take a steamy-hot shower will release the crinkle. You can also throw the item in your dryer along with a wet item. The wet item will produce steam to de-wrinkle the dry item.
In the end, steam washers and dryers simply add more options and flexibility to solve your laundry quandaries. To get more dirt on cleaning methods and steam technology, take a gander at the links on the next page.