You know that dishwasher detergent is the stuff that actually cleans gunk off your dirty dishes, but chances are, you probably have a hazier understanding of what so-called "rinse aid" is for. If you’ve purchased a dishwasher recently, you probably received a free sample of it, or noticed that your new machine warns you when you’re running low.
But what exactly is rinse aid, and why do you want it in your modern dishwasher?
What Does Rinse Aid Do?
Despite its name, rinse aid actually doesn't have anything to do with rinsing your dishes. Instead, it helps remove water from flatware, plates, bowls, and glasses. Really, it's more of a drying aid. Why don't they call it "Dry Aid?" We don't know, but it would have been a lot more accurate.
Rinse aid contain chemicals called surfactants, which lower the surface tension of water. So instead of forming droplets, the water spreads into thinner sheets that roll right off your dishes. If you’ve ever used Rain-X on your car’s windshield, you'll have a good idea of what this looks like.
Ultimately, this means that your dishes will dry much more quickly.
Fewer Spots on Glasses
The other perk is that rinse aid's hydrophobic—or water repellant—properties prevent your dried dishes from showing water spots, which are caused by minerals left behind as water evaporates off a surface. In a perfect world, the water in our pipes would be pure and free of minerals, but in the real world even water that isn’t considered “hard” still contains trace amounts of limestone or chalk.
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What's In Rinse Aid?
Popular brand-name rinse aids like Cascade and Finish Jet-Dry make use of citric acid and alcohols, along with a handful of less familiar–sounding chemicals (sodium cumene sulfonate, anyone?). The Environmental Working Group, which rates household products on safety for humans and the environment, graded them D and F, respectively. This rating is also affected by how openly the products disclose their ingredients.
However, "greener" brands like Seventh Generation and The Honest Company make rinse aid derived from a plant-based formula. Their products earned A and C grades from the EWG, in large part because full ingredient lists are easy to find on their sites, and they're notably shorter than those of the more well-known brands.
Should I Use Rinse Aid?
For the most part, if you’re not seeing water spots and you’re satisfied with your dishwasher’s drying abilities, you can do without rinse aid. But because "wet dishes" are the most frequent complaint among surveyed dishwasher owners, you should at least give rinse aid a try.
Alternatively, certain brands of dishwasher tablets have an “all-in-one” mixture that contains both detergent and rinse aid, saving you from buying a bottle of rinse aid every 60 loads or so.
Finally, some homeowners wary of the chemicals that may or may not be lurking in commercial rinse aid have successfully solved their hard water spotting problems with regular old white vinegar. We haven’t tried it ourselves, but we'd speculate that loading vinegar in your rinse aid dispenser is probably not a great idea. (Hint: It’s really acidic.)