When considering which items can and should be put in the washer and dryer, there are two parts to the equation. First, knowing how to properly care for your clothes and home textiles: It’s one of the most important parts of preserving their quality and extending their lifespans, allowing you to also reduce unnecessary waste and overconsumption in the process. Second, putting the wrong items in washing machines and dryers can cause damage to the appliances themselves, resulting in costly repairs or replacements.

This list serves as a general primer on items to avoid, but it’s not exhaustive, and there are always exceptions. So, when in doubt, always consult the care tag of the item you’re planning on washing. (Pro tip from our Managing Editor Erin Alexander’s mom: Print out a guide to all the little symbols that appear on care tags, and keep it near your washing machine—that way, it’s always a breeze to double check if an item is washer- or dryer-safe.)

1. Swimwear

“It may sound counterintuitive, but swimsuits should be hand-washed,” says Elizabeth Yunmi Hokyo, senior editor at Schoolhouse. “Reason being—the washing machine’s agitator can ruin the elasticity of bathing suits, damage the straps, or wear down the fabric.” The same logic applies to the dryer—in order to prevent warping or other damage, always let swimwear air dry.

2. Anything covered in pet hair

If you have an item covered in pet hair, you’ll likely want to give it a good cleaning—but you should think twice before tossing it in the washing machine. “I’d recommend against putting anything with too much pet hair on it in the washing machine, at least without cleaning it off first,” says frequent Home52 contributor Camryn Rabideau. “I have two long-haired dogs and a cat, and I always make sure to vacuum or use a hair remover on their beds and blankets before washing. Otherwise, all that hair can end up clumping in your washer or, worse, clogging up your drain pipes.”

3. Suede & Leather

Leather, and especially suede, are (in most cases) notoriously incompatible with water. “We don’t recommend putting suede shoes in the washing machine or hand washing them in soap and water,” explains Nike, with respect to the brand’s suede sneakers. “Suede absorbs water, so washing a pair of suede shoes with water can actually cause stains to set in the fabric.” Likewise, prolonged exposure to water strips leather garments of their natural oils, causing them to crack. Dryers, in turn, will dry out leather and suede, causing the former to shrink and crack and the latter to become “stiff and misshapen.”

4. Flammable Stains

From motor oil to paint thinners, there are a surprising number of flammable household substances that can end up on your clothes. If your clothing becomes stained with something flammable, it shouldn’t go in the washing machine—and it definitely shouldn’t, under any circumstances, go in the dryer. The heat from these appliances could cause the garments to combust, resulting in a fire or explosion.

5. Garments With Intricate Beading & Embellishments

If you put beaded, sequined, or otherwise-embellished items in the washing machine, there’s a chance they’ll “get torn up,” says Erin’s mom, who’s an at-home laundry pro. The dryer has similar risks, plus those that result from its warm temperature: Even on a low setting, the heat from the dryer can melt glue and any plastic components on the garment, notes Elizabeth.

6. Suits & Formalwear

Not only are these garments made of delicate fabrics that can become damaged in washing machines and dryers, they’re also typically made with interfacing, which gives them their internal structure and shape. When exposed to water and agitation, the interfacing can become misshapen and even fall apart. The dryer, with its high temperatures and constant motion, creates similar problems.

7. Waterproof & Water-resistant items

Like swimsuits, this one might seem counterintuitive, but waterproof items should steer clear of washing machines. “Water-proof textiles like mattress covers should absolutely be hand-washed and air-dried at all costs,” says Elizabeth. “The material can trap water, causing an unbalanced spin cycle while wearing down the fabric’s water-resistant properties.”

8. Memory foam

Most memory foam is incompatible with washing machines and dryers: All the motion of these appliances can cause the foam to weaken, break, and even disintegrate. The heat from the dryer, meanwhile, can cause the flammable materials in memory foam to catch fire.

9. Wool

Wool is one of the more debated items on this list, but according to Elizabeth, it’s better to be safe: “When in doubt, hand wash your sweaters! It will save you in the long run.” Specifically, she says, a washing machine’s agitator has the potential to disrupt and damage delicate knit textiles. The same goes for tossing wool garments in the dryer. “Some wool garments say that you can tumble dry on low heat, but honestly, I wouldn’t risk it,” says Camryn. “Wool fibers are extremely prone to shrinkage when exposed to heat, so I always air dry wool clothing.”

What’s your best laundry tip? Share in the comments!