If you're finding a lot of food stains on your dishes after a session on the dishwasher, the problem may be your detergent. Dishwasher detergents aren't just a simple soap; they're a complex and ever-changing formulation of chemicals that work together to get the job done.
To make it even more confusing, dish detergents can come in powder, liquid, or tabs. You're not alone if you've caught yourself frozen in the supermarket aisle trying to parse the difference between ultra, super-ultra, and mega-ultra variations. Every type of detergent has pros and cons, though most experts recommend tabs and gel pacs for peak performance.
By the end of 2015, 70 percent of all dishwasher detergent sales were in tab or pack form, according to Nielsen/IRI. Gel detergents accounted for 20 percent of sales, while powdered detergent had fallen to a mere 10 percent.
Here’s the thing: The two primary active ingredients in dishwasher detergent are bleach and enzymes. Bleach eradicates stains like coffee and tea, while enzymes eat away at proteins and solids. Both are important components, and you’ll find them in powder and tab detergents. But enzymes and bleach can't play together in gel products because most bleaches, in liquid form, will kill enzymes.
Diane Hoffmann is a senior strategic alliance manager with Reckitt Benckiser, which makes Finish for dishwashers. She says that consumers got it into their minds that powder doesn’t dissolve, which led to the embrace of gels. “But of the two agents, bleach and enzymes, liquid detergents can only have one or the other," she confirms. "You’re not going to get rid of a starch-based stain like potato with bleach.”
But while consumers have been on a steady march away from powdered detergent, especially since the introduction of tabs in the mid-1990s, many haven’t quit their love affair with gel detergents.
Alvin Chan, senior product manager for Dish Care at Bosch parent company BSH Home Appliances, says consumers are generally unaware that gels don't offer the same cleaning cocktail as powder and tabs. “Powdered detergent is a perfectly suitable option when properly stored and used,” he adds.
One of the reasons that powder may have lost its luster is poor storage habits. “Detergents are water-activated, so once a box gets wet, all the cleaning that can happen, happens in the box,” explains Hoffmann. And where do most of us store dishwasher detergent? Under the sink, an area that’s bound to get wet once in a while.
Meanwhile, the biggest argument against tabs is that they are more expensive, per load, than powders—as much as double the cost. But the convenience factor is a clear win. Not only are they less messy and less complicated, but they often take up less shelf space at home.
Tablets and gel pacs generally deliver top performance
Ultimately, it seems clear that tabs and gel pacs deliver the best overall package of cleaning power, convenience, and reliability—as long as you don't mind paying a price premium. Powder is a good (and inexpensive) second choice, while gels should be your last resort.
Powder detergent might work best for really hard water
Chan says that one place where powder may have a slight advantage over tabs or gel pacs is in homes with hard water. Hard water causes limescale deposits, which create white spots, streaks, and cloudiness on glasses.
“Water hardness level directly impacts a dishwasher’s performance,” explains Chan. “In extreme hard water areas, powder may provide improved performance because it allows the user to adjust the amount of detergent used.”
Chan notes that a few dishwashers (including some by Bosch), have a built-in water softener that uses a special salt to adjust the water hardness for optimal performance. And there are supplemental products from Finish and Cascade that can help with hard water issues.
We also wondered whether one type of detergent might be more environmentally friendly than the others. Since phosphates fell out of favor with manufacturers in 2010, detergents have become far less toxic than they once were. But otherwise, what goes down the drain is largely dependent on the additives used by manufacturers. These chemicals, like sodium polyacrylate and zinc carbonate, vary from brand to brand.
Individually wrapped, gel packs and tabs probably involve more packaging per load than a spoonful of powdered detergent. But Mandy Ciccarella, communications manager with Cascade detergent maker Procter & Gamble, says the company’s long-term corporate plan is to achieve 100 percent renewable or recycled material in its products and packaging, with zero waste going to landfills.
“To help realize this vision, we are developing products that rinse faster, clean better in cold water to save energy, and use less packaging through more product concentration,” adds Ciccarella. “For our packaging, we are investing in improving our recycling rates to help reduce waste.”
But perhaps the biggest carbon footprint comes courtesy of shipping. And because tabs are more concentrated than powder and gel—they’re smaller and more lightweight, per wash—they require less energy to ship.
For an inside look at how dishwashing detergent works, check out our Science Blog for an explainer on surfactants and enzymes.