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Liquid Dish Soap

By Cook's Illustrated Published April 2014

How we tested

As much as we love our dishwashers, when washing delicate china, wood cutting boards, sharp knives, and pots and pans, we still rely on soap and sponge. The last time we tested dish soaps, in 2007, we liked Method Go Naked Ultra Concentrated Dish Detergent best. But it was recently discontinued, so we are revisiting the subject.

We were surprised to find a host of new soaps designed for people who scrub dishes under a running tap rather than fill the sink with soapy water—the more traditional method. So we decided to include three such products: two with pumps that foam straight from the bottle, and one with a special motion-sensor system for germ-free dispensing. We also found an unusual dishwasher detergent/dish soap hybrid. Four of the seven products also make some claim to being environmentally friendly, so we pitted them against the benchmark for traditional liquid soaps—the national best seller Dawn Ultra.

In the kitchen, we gleefully made a mess, burning skillets with measured portions of hard-to-clean foods like béchamel sauce and chicken teriyaki. Controlling for the amount of soap, water temperature, and type of sponge, we washed the pans using both the fill-sink method and the rinse method, counting the strokes needed to get each pan clean. Our best soaps required fewer than 70 strokes, while others needed anywhere from 85 to 100. One soap consistently required more than 100 strokes and even then left a film of oil. What accounted for these differences?

Oil and water repel each other, so soap makes washing dishes easier because it contains surfactants, tadpole-shaped chemicals with water-loving heads and oil-loving tails that encourage water and fat to mix. Surfactants can be made from plants (for all-natural cleaners) or petroleum, but according to Brian Grady, director of the Institute of Applied Surfactant Research at the University of Oklahoma, the origin of surfactants doesn’t determine the effectiveness of the soap. “There’s no inherent advantage of one over the other,” he said. “It comes down to the individual formula and overall quantity of surfactants.”

We turned to a simple science project to measure the power of each product. Surfactants make water “wetter” by lowering its surface tension, allowing tightly packed water molecules to spread out and make room for dirt and grease. We mixed a measured solution of soap and water in plastic cups and suspended a strip of paper bag so that it was just touching the surface. A solution with strong surfactants (and therefore lower surface tension) will allow the water to climb the strip of paper; the higher it travels the stronger the surfactants.

After an hour, the two top-performing soaps climbed an average of more than 40 millimeters, while plain water traveled only 10 millimeters. Our poorest-performing soap (the same product that left dishes filmy with oil) climbed just 11 millimeters. Despite the manufacturer’s claims, it didn’t work in the dishwasher either. We used the data from this test to calculate the strength of surfactants of each soap.

Scent also mattered to our testers, although we gave it less weight in our rankings than washing ability. We asked each soapmaker for its most popular fragrance and had 21 test kitchen staffers sniff each product mixed with water. Testers preferred lightly scented soaps.

All but one of our soaps performed reasonably well, though we’re not sold on foams, even for tap runners. Our recommended soaps worked no matter how we washed with them. In fact, all the products that we tested performed best when we used the fill-sink approach. Why? Since surfactants are dispersed throughout the water, the surfactants are cleaning your dishes even when you’re not scrubbing.

In the end, one soap whipped both innovative products and a traditional favorite, no matter our washing technique, and we liked its smell, too. From now on, we’ll use our winner when we have a sinkful of dirty dishes.

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The Results

Winner
Recommended

Design Trifecta 360 Knife Block

Admittedly expensive, this handsome block certainly seemed to live up to its billing as “the last knife block you ever have to buy.” The heaviest model in our testing, this block was ultrastable, and its durable bamboo exterior was a breeze to clean. Well-placed medium-strength magnets made it easy to attach all our knives, and a rotating base gave us quick access to them. One tiny quibble: The blade of our 12-inch slicing knife stuck out a little.

$248.64*
Recommended

Schmidt Brothers Downtown Block

This roomy block completely sheathed our entire winning knife set using just one of its two sides—and quite securely, thanks to long, medium-strength magnet bars. Heavy, with a grippy base, this block was very stable. An acrylic guard made this model extra-safe but also made it a little trickier to insert knives and to clean; the wood block itself showed some minor cosmetic scratching during use.

$141.90*
Best Buy
Recommended

Schmidt Brothers Midtown Block

This smaller version of the Downtown Block secured all our knives nicely, though the blade of the slicing knife stuck out a bit. With a base lined with grippy material, this block was very stable. An acrylic guard afforded extra protection against contact with blades but made it a little harder to insert knives and to clean; the wood itself got a little scratched during use.

$67.99*
Recommended with Reservations

Swissmar Bamboo Magnetic Knife Block

This small, scratch-resistant model had a stable, rubber-lined base and could hold all our knives, though the blade of the 12-inch slicing knife stuck out a bit. But inch-long gaps between its small magnets made coverage uneven and forced us to find the magnetic hot spots in order to secure the knives. Its acrylic guard made it safer to use but harder to insert knives and to clean.

$49.93*
Not Recommended

Messermeister Walnut Magnet Block

This handsome block was done in by its shape—a tippy, top-heavy quarter-circle that wasn’t tall or broad enough to keep the blades of three knives from poking out. It lacked a nonslip base, and its extra-strong magnets made it unnerving to attach or remove our heavy cleaver. Finally, it got a bit scratched after extensive use.

$129.95*

Epicurean Standing Knife Rack 12"

This magnetic block sheathed all our knives completely, though with a bit of crowding. But it was hard to insert each knife without hitting the block’s decorative slats on way down, and because the block was light and narrow, it wobbled when bumped. Worse, we couldn’t take it apart, so splatters that hit the interior were there to stay. Additionally, the outside stained easily, and when we wiped it down, the unit smelled like wet dog.

$99.95*

Kapoosh Rondelle Knife Block

This model stabilized knives with a mass of stiff, spaghetti-like bristles that shed and nicked easily after extensive use, covering our knives with plastic debris. While all our knives fit securely, several of the blades stuck out, making this unit feel less safe overall. Finally, though the bristles could be removed and cleaned in the dishwasher, their nooks and crannies made this block hard to wash by hand.

$24.99*

Kuhn Rikon Vision Knife Block, Clear

This plastic block required us to aim each knife into the folds of an accordion-pleated insert that was removable for easy cleaning but got nicked easily with repeated use. Because we could only insert the knives vertically, longer knife blades stuck out; a cleaver was too wide to fit. The lightest model in our lineup, this block was dangerously top-heavy when loaded with knives.

$35.88*