So, you want to lengthen your lashes, or, at least, you’re thinking about it. Maybe applying several layers of mascara is not exactly cutting it, or maybe you just want to feel put together without having to apply a stitch of makeup. Either way, we’re conducting a full investigation into eyelash extensions, the buzzed-about, and sometimes polarizing lash treatment that It girls and celebrities alike rely on to nail that doe-eyed beauty look.  Anyone who’s heard of eyelash extensions is likely also familiar with the cautionary tales that surround it, which, for the most part, detail natural eyelashes falling out as a result of the extensions. In actuality, when applied correctly by a licensed esthetician or cosmetologist, eyelash extensions are totally safe and shouldn’t do any damage to the natural lash. Still, it’s likely that you may want a few questions answered before you sit down in that salon chair.  To help us get the 411, we called on entrepreneur, celebrity lash expert, and founder of Star Lash Beauty Bar, Yris Palmer. Not only is she one of the top lash gurus out there, but she’s also responsible for architecting fabulous lash looks for A-listers such as Kylie Jenner, Chloe Bailey, Halle Bailey, Winnie Harlow, and more. In short? She’s kind of a big deal. Keep scrolling for her expert breakdown of the most important things to know about eyelash extensions.

Eyelash extensions are the process of lengthening the natural lash by bonding strands of mink, silk, synthetic, human hair, or horsehair to each lash. Using different types of professional glues (Star Lash’s formula is formaldehyde, gluten, paraben, latex, and cruelty-free), each faux lash is hand-glued to an existing lash, making for a safe and natural-looking end result. “First thing I tell clients is that lash extensions are very addicting and life-changing,” says Palmer. “Once you start, you won’t want to stop. Literally! They make your life so much easier, you feel put together with zero makeup on.” 

Many weigh extensions against the equally buzzy lash lift treatment, which involves using a chemical serum to posture your lashes upward instead of outward. According to Palmer, “Eyelash extensions are the only way to make your lashes longer and fuller. You cannot achieve this any other way,” she tells Who What Wear. Extensions are also designed to augment and build upon the curl of your lash, making for a fluttery, fluffy look instead of the spiky look that is sometimes associated with lash lift treatments.

“Eyelash extensions are suited for most people with healthy lashes,” says Palmer. “However, if you have few or no natural lash hairs, if your lashes are weak, in poor condition, or if you have severe allergies, then eyelash extensions may not be for you. We also can’t do eyelash extensions on any patients undergoing chemotherapy or with any medical conditions experiencing hair loss,” she explains. Before your session, it’s worth strengthening your natural lash with a trusted lash-enhancing serum. Even though these at-home treatments tend to be a bit splurgier price-wise, it’s well worth the extra cost to ensure that you have a great foundation to build upon with extensions. After all, it’s all about doing everything possible to avoid damaging your natural lashes.

“The application process takes anywhere from one to two-and-a-half hours,” Palmer says. “Individual lash extensions are dipped into a medical-grade adhesive and bonded to your natural eyelash. This process is done one lash at a time, so it can take a while.” If you’re worried about spending that much time out-of-commission, just count it as a well-earned moment of solace. “The process is painless and most clients take this time to relax, sleep, or vent about their lives,” Palmer adds.

One of the best things about eyelash extensions is how customizable they are. “The finished look really depends on the look the client was going for,” says Palmer. “Most people come to me and ask for the wispy look, so in that case, it’s definitely imperfect with different variations in lengths. I do love a fluffy look—I usually always skip a length in-between sizes to give the eye more dimension. I don’t like a uniform look or a ‘broom’ look, as most lash artists call it when all the lashes are the same length.” A great way to ensure you end up with exactly the lash look you’re going for? Scroll through the ‘gram and collect photos to share with your artist. This way, they can envision exactly what you want without any guesswork.

“They can last about four to six weeks, depending on how careful you are,” says Palmer. “Every person is different. It really depends on your lifestyle.” As an example, paler points out that those who regularly break a sweat in the gym or saunas may find that the adhesive binding the extensions to their lashes loosening faster, leading to more fallout. “[Others] are really careful with their lash extensions and come back every four weeks for a fill,” she says. So, when deciding on the style of your extensions, keep in mind the kind of wear and tear you’ll be putting them through for the best results.

Eyelash extensions require some extra care that you might not be familiar with up top. Here are some hard-and-fast tips for maintaining them:

For the first 24 to 36 hours after your session, avoid getting the lashes wet and avoid humid environments. This way, the adhesive can cure as well as possible.

Avoid anything that may rub up against your eyes, which might mean waiting until allergy season has come and gone if you suffer from itchy eyes at certain times of the year. You should also try not to sleep face-down, as the friction with your pillowcase could cause the lashes to twist out of place.

When cleansing or removing makeup, opt for oil-free products, like foaming cleansers.

Try to gently brush the lashes for 10 to 15 seconds per day. Position a clean spoolie brush mid-way through the lash shaft and move it upwards towards the ends of the lash. Again, you’ll need a clean spoolie every time to avoid getting bacteria in or near the eye.

To avoid weakening the adhesive, only use water-based mascaras on your lash extensions. YSL’s Volume Effet Faux Cils Mascara ($29) is a great option.

Next: These Falsies Are So Good You’ll Forget How Much You Miss Your Lash Extensions