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Car seats inevitably get messy. They are a mobile chronicle of life with little ones—the pulverized party snacks, that blotch of sunscreen from a day at the beach, those muddy post-soccer-practice shoe prints, a streak of dried spit-up from the bumpy ride to Grandma’s.

Attempting to erase these archives can be daunting: Uninstalling the car seat, taking it apart, cleaning it properly, and then figuring out how to put it all back together again is a chore. And since this is a device that can save your child’s life, it’s important to get it right.

Most car seats are made from fabrics and materials that are meant to survive a whole host of indignities. How often you choose to clean a car seat will depend on your circumstances, as well as your individual threshold for grime. Certain messes, such as vomit, urine, or a diaper blowout, should be addressed as soon as possible because if they are left to linger, they could weaken the straps—not to mention create an awful smell. But the bits of dirt, Goldfish crumbs, and sunscreen streaks can wait until your family’s personal limit has been reached, whether that takes months or years.

When the time comes, the right approach for tackling the mess will be dictated by which car seat you have. Each manufacturer has a unique set of guidelines for cleaning its seats, and these must be followed. Ignoring the guidelines could result in damage to the seat’s materials, such as weakened straps or reduced flame retardance, and could compromise safety. We consulted two experts to get advice and cleaning tips that can be used in conjunction with the instructions for your car seat. Emily Marks is a cleaning professional for BabyQuip, a baby-gear rental and cleaning company, and Alisa Baer is a nationally certified child passenger safety instructor and co-founder of The Car Seat Lady.

Note: Should you decide to outsource the cleaning to a professional, be sure to find a service that has expertise with car seats and is committed to following manufacturer guidelines. Also, you may want to take “before” pictures of the car seat (front and back) so that when you get it back, you can check that it’s been reassembled properly.

Depending on what type of cover your car seat has, the active labor involved in scrubbing it, removing the cover (and straps) from the frame, washing it thoroughly, and wrestling it back on (arguably the hardest part) could take a few hours or more. And since most car-seat covers are not dryer-safe, it could take up to a day for your cover to air-dry completely before it can be put back on.

With the cover still on the car seat, start by vacuuming up debris in the crevices with an upright vacuum, a shop vac, or a hand vac. When you’re finished, keep the vacuum cleaner handy because you’ll need it again later.

Marks tackles stains by using a small scrub brush (a toothbrush also works) dipped in a mixture of castile soap and water. For tougher stains, like mineral sunscreens, use a mix of dish soap (Marks uses Dawn) and water instead of castile soap. Avoid getting soap on the buckles. Soap and other residue could prevent the buckles from latching correctly.

If you’re spot-cleaning only and not moving on to the next steps, then you can finish up by using a moist rag to remove any excess soap from the cover. For easy messes, like crumbs or a bit of dried mud, spot-cleaning may be enough to get your seat looking good. But for bigger messes, it may be necessary to remove the cover completely.

Many seats need to be uninstalled from the car in order to remove the cover. If you are uninstalling a car seat, Marks points out that this is a handy time to double-check when your seat expires—the date is usually on the bottom or back of the seat. Don’t keep a car seat past its expiration date: After years of use, changes to the seat’s integrity can occur, potentially making it no longer safe in case of an accident. Also, new models may have updated safety features.

It can be helpful to record a video as you’re removing the cover. This way you’ll be able to remember the steps involved when the time comes to put it back on correctly. Alternatively, you can search online for manufacturer videos that demonstrate how to put the cover back on your specific make and model of seat.

Before washing, check the manufacturer’s instructions. Some cleaning agents can remove or react with flame-retardant chemicals—or you may be advised not to immerse the cover in soapy water at all.

If your cover isn’t machine-washable, put it in a bathtub, large sink, or bucket with warm water and a bit of soap. Then swirl it around or stomp on it. You may also want to let it soak for up to 15 minutes before rinsing.

If the cover can be machine-washed, follow the manufacturer's instructions about water temperature and detergent. Some detergents, including those with bleach, can react with flame-retardant chemicals.

Most car-seat covers can’t go in the dryer, so the back of a chair or a drying rack are good places to air-dry your cover. If you need to get your car-seat cover back on ASAP, you can speed up the process by putting the seat cover in front of a fan or in direct sunlight. This can also help eliminate some bacteria. Just don’t use anything with concentrated heat, like a blow dryer, since that could damage the fabric or cause shrinkage.

Make sure the cover is totally dry before putting it back on. Otherwise it could trap moisture within the seat, which may cause mold, metal parts to rust, or the straps to weaken.

To make sure you put straps back in the correct orientation later, take a picture of the straps before you remove them from the frame of the seat. The straps are crucial for your child’s safety.

Avoid submerging the straps in water, and do not use chemicals (like bleach) on the straps. Both water and chemicals can affect the integrity of the straps. If there is vomit (or worse) on the straps, scrub the area with water and a bit of soap, being careful not to fully soak the straps. If the straps are heavily soiled, Baer noted that many manufacturers sell replacement straps. It’s best to buy directly from your seat’s manufacturer and double-check that they match your exact model.

Once the cover has been removed, use the vacuum to suck any debris off of the car-seat frame. You can also use this opportunity to attack the area in the car where the seat usually rests. Then use a damp rag to wipe down any icky surfaces on the frame. Don’t get the exterior of the seat too wet, though. That could cause the manufacturer’s labels—which provide installation assistance, expiration dates, and identifying information in case of recall—to peel off.

First, make sure the straps are put back on in the same position they were in before cleaning and without any twists. Next, if there is more than one slot for the crotch strap, you may want to check that it is positioned correctly for your child (consult the manufacturer’s instructions for fit guidelines).

When you’re ready to put the (fully dried) cover back on, consult the video you took upon removal, or the manufacturer’s video, to help you get it on properly. Finally, before you reinstall or bring the seat to a professional for installation help, have your child sit in the seat to confirm that the straps are adjusted to the right height. The straps should be at or below the shoulder for rear-facing seats and at or above the shoulder for forward-facing ones.

Moving forward, you can help keep a car seat tidier by giving your kids spill-proof water bottles and covered snack cups. If your child or toddler has frequent spills or car sickness, an extra-large bib, like the Bumkins SuperBib, can help catch the mess. For an older child who struggles with car sickness, a disposable bag with a plastic ring top (to hold while vomiting) and closure system (for afterward) can be a game-changer.

To prevent fresh messes from soaking into the seat, you may also want to carry a small towel or baby wipes (but not antibacterial wipes, which may contain chemicals that impact the straps or fabric) to sop up a spill.

Although the concept is appealing, so-called “universal” car-seat covers should be avoided, since third-party accessories aren’t crash tested and may affect the seat’s performance in an accident. But you can check to see whether the manufacturer of your car seat makes a protector that’s compatible with your model. For example, the Britax Seat Saver is a waterproof liner that’s approved to work on all of the brand’s seats.

Christina Szalinski is a freelance science writer with a PhD in cell biology.

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