If the dishes are not coming out of your dishwasher as clean as you'd like, you might be tempted to blame the appliance or your brand of detergent. But the problem might just be in the way you're stacking the machine.
Fortunately, it's easy to maximize its effectiveness by taking a few simple steps. HowStuffWorks talked to Morgan Brashear, Cascade research scientist with soap giant Procter & Gamble to get the lowdown on the dishwasher scrubdown.
Step 1: Know What's Dishwasher Safe and What Isn't
Some of the items on the no-fly list are fairly obvious. Cast iron will rust and lose seasoning if placed in a machine; fine china and crystal cannot handle the intense heat of the dishwasher. But here some other items to leave out:
- Insulated travel mugs — the high heat of the machine can ruin the vacuum seal and reduce the mug's ability to retain heat
- Aluminum pots — very prone to scratching and can develop a dull finish or turn a blackish color
- Wooden spoons and cutting boards — heat and humidity can crack word and germs may enter them
Although most nonstick pans on the market today are dishwasher-safe, Brashear cautions people to check washing instructions first, and limit dishwasher time even if it is allowed. "Any frequent washing in high temps of nonstick pans can cause the coating to wear off," she says.
Step 2: Skip Your Pre-wash
You have the best of intentions when you rinse your dishes before stacking them, but the habit is unnecessary and counterproductive. Most modern dishwashers come with a sensor that evaluates the water to determine how long the cycle should be and how much water is necessary to produce a thorough clean.
"Even if you press the 'normal cycle' button, the length and temperature of the cycle can vary, depending on what the sensor detects. It does this through a measure of turbidity (how cloudy the water is) during the pre-rinse cycle – before the detergent is even released into the water," Brashear explains. "The water in the pre-rinse will remove any loose soils the same way they would be removed with water alone by pre-washing. The machine will then recognize that there is food present and will run a more thorough cleaning cycle."
She cautions, "If you pre-wash all of your dishes except for one casserole dish with some baked-on cheese, nothing will come off in the pre-wash ... and it will run a shorter cycle, leading to a less thorough clean and potentially a failure on that one casserole dish."
There are components in your dishwasher detergent like chelants and enzymes, which are designed to break up food particles. "Since the job of these enzymes is so specific, if that starch or protein isn't present, they do not have another job they can do. So, they are either simply removed with the wash water or, in some particularly problematic situations, the detergent can appear to deposit onto the dishes, leaving a powdery residue," says Brashear.
The general rule of thumb? "Scrape off all of the chunks or things that might clog up the machine. Any sauce or crumbs we recommend to keep," she explains.
Step 3: Load it Right
Dishwashers may vary, but the major principles of smart loading apply to all:
First, load dishes to face the center of the machine. The spray arm sprays out in a circular motion, so plates that aren't facing the center will get a heavy cleaning on the wrong side.
Heat-sensitive plastics should go on the top rack, to avoid risk of melting since the heating unit is located on the bottom.
Glasses should also go on the top rack, but place them between the tines, rather than over them. "If the tines are touching the glass there's going to be a spot (where water gets trapped) and it'll dry that way," Brashear explains.
Forks and spoons should face up to minimize the risk of "nesting" inside a packed utensil basket. This also keeps the basket from getting in the way of the wash, making sure the head of the utensils get nice and clean. If you have a ton of silverware to wash, try to spread out similar pieces (to avoid nesting) or alternate them head down, head up. Along the same lines, resist the urge to overload the dishwasher. If one item is completely blocking another, neither one will get truly clean.
Step 4: Maintain Your Machine
Your dishwasher actually has a filter that needs to be removed and cleaned out on occasion. Most soils, like sauce or crumbs, will slip right through the filter, but any errant chunks of food will get caught and clog it up. To clean, simply remove and rinse with a little bit of dish soap. Be sure to rinse it completely or it will cause sudsing during the next cycle.
Limescale (especially in areas with hard water) and grease can also build up in the spray arms and filter over time. Brashear recommends monthly use of a dishwasher-specific cleaner to prevent problems from escalating.