Things you should never put in the dishwasher (and the weird items that are OK)

An energy-efficient dishwasher can save close to 5,000 gallons of water a year compared with hand-washing, according to the Environmental Protection Agency. With stats like that, we understand if you’re tempted to throw everything in the dishwasher.

But hold on—in your zeal to get out of washing dishes by hand, you could be ruining several very important kitchen items. Find out what you should not put in this appliance, along with some household items you probably didn’t know you could load in the dishwasher.

Aluminum

The aluminum items themselves will be fine, but the aluminum will ruin the finish on other items in the dishwasher, says Chris Thornton, senior manager of product training at Samsung. For example, if you have dishes with a printed gold rim, aluminum will discolor them.

Cast iron

There are few cooking items more useful than a cast-iron skillet. However, basic cast-iron care dictates you should never put it in the dishwasher.

“The dishwasher will strip the pan of its seasoning and can potentially rust the iron in its natural state,” says Doug Rogers, president of Mr. Appliance, an appliance repair service.

He recommends using a paste of coarse kosher salt and water to scrub the pan. After it has dried, apply a light coating of oil.

“This will help the cast iron to avoid rust while retaining seasoning,” he says.

Cheese grater

Your dishwasher’s good—but not good enough to remove all the hidden cheese in the grater holes.

“To make sure there’s no hardened cheese mixed with your next meal, wash your cheese grater by hand with a soapy sponge,” says Rogers.

Nonstick pots and pans

Nonstick pans are a lifesaver when it comes to making grilled cheese that doesn't leave a mess sticking to the bottom of the pan. But you'll want to refrain from putting your nonstick cookware in the dishwasher.

"Unless the manufacturer states the item is dishwasher-safe, over time, the dishwashing process can break down the nonstick coating, causing it to potentially flake off and ruin the nonstick finish,” Rogers says.

Plastics with a temperature tolerance below 194 degrees

Thinly made plastics could be damaged at high temperatures, Thornton says—and they tend not to wash and dry well in the dishwasher at any temperature.

Sharp knives

In the dishwasher, your knives are rubbing up against other cutlery, which can cause them to become dull, says Rogers.

“Unless your dishwasher has a rack specifically for knives, don’t run the risk of nicking other surrounding items,” he says.

Tin

Tin can rust in the dishwasher. Thornton recommends washing tin items by hand and then drying them immediately.

Wooden cooking items

Those salad tongs and cooking spoons are hand-wash only.

“Any type of wood has the potential to crack in the dishwasher," Thornton says.

Wooden cutting boards are also subject to warping as a result of the hot water and heat. Rogers recommends washing them with warm, soapy water in a sink or bowl and then air-drying them. You can also apply a thin coat of mineral oil on a monthly basis to make sure your wooden items don’t get too dry and start to crack.

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Items you can put in the dishwasher

If you don’t like washing dishes by hand, you'll be happy to hear that your dishwasher can handle cleaning other household items you wouldn't typically think to put in the dishwasher.

Glass lightbulb covers

Have you ever stared at the light fixtures in your home and wondered how the heck you're going to get them clean beyond the weekly dusting? Kelly Tucker, an expert from the Whirlpool Corporation Institute of Home Science, says glass lightbulb covers can be thrown in the dishwasher.

“Grease and humidity can cause dust to build up on these light fixture and ceiling fan covers,” Tucker says. She recommends loading them in the dishwasher to get the covers clean and sparkling again.

Sturdy plastics

Tucker says coolers and highchair trays can be safely placed in the dishwasher—if they can fit.

“Sturdy and larger items can be loaded into the bottom rack for easy cleaning. Just remember to turn off the heated dry option, and always check the manufacturer’s recommendation first,” she says.

Barbecue grill grates

Grill masters, rejoice! We all know that a grill is one of the toughest things to clean, but Tucker says you can throw that grate right in the dishwasher.

She recommends selecting a longer wash cycle with heat drying, since this can help remove the grease.

Plastic toys

Bath toys like rubber duckies and other plastic items your kiddos love can be breeding grounds for mold. Toys that are 100% plastic—without battery compartments—can be thrown in the dishwasher, according to Leanne Stapf, vice president of operations at the Cleaning Authority. Just don't use heat drying, which could melt them.

To sanitize bath toys, Stapf recommends first soaking them for 5 to 10 minutes in a solution of either water and a half-cup of vinegar, or water and a half-cup of bleach. Then run the toys in the dishwasher to remove the solution's residue and let them air-dry.

Sponges

Your trusty sponge needs to be disinfected and cleaned regularly.

“After choosing the ‘heated dry’ setting, lay the sponge on the top rack until the cycle is complete,” Stapf says.

Stapf adds that these other items can also go in the dishwasher:

  • Contact lens case
  • Shower head
  • Hairbrushes and combs
  • Rubber flip-flops, canvas sneakers, and baseball caps
  • Mouth guards
  • Makeup brushes
  • Refrigerator shelves

The article originally appeared on Realtor.com.