An Insider’s Guide to Eyelash Extensions

An Insider’s Guide to Eyelash Extensions featured image
Photo Credits: Rosdiana Ciaravolo / Contributor/ Getty Images | Image Used for Illustrative Purposes Only

If you like the idea of waking up with longer, thicker eyelashes (without applying any product), semipermanent lash extensions are a game changer. They can not only make a dramatic difference in your look, but also your beauty routine. But, before you make your appointment, there are some important factors to consider. Here, experts detail the different types of extensions, what happens during an appointment and how to take care of them.

Featured Experts:

  • Clementina Richardson, a lash technician, lash expert and founder of Envious Lashes in New York
  • Michelle Nguyen, a lash technician, lash expert and founder of PLA
  • Sophy Merszei, a cosmetic chemist, lash expert and owner of NovaLash

Types of Eyelash Extensions

Different materials are used to make lash extensions, which affect how they look and feel. These are the most common types.

Korean PBT

“At PLA Beauty, we make our lashes from Korean PBT, or polybutylene terephthalate,” says lash technician and expert Michelle Nguyen, founder of PLA, a beauty supply company specializing in lash extensions. “This is a high-quality plastic material, and the most common material for lash extensions. Synthetic lashes are a better option because they are uniformly made, hold their shape over time, and are less likely to cause reactions.” There are also different qualities of Korean PBT. For example, Nguyen says different brands use marketing terms such as “super mink” or “silk” or “cashmere,” but they all are Korean PBT. The primary difference between these subcategories is the weight of the lashes.

According to Sophy Merszei, a cosmetic chemist and owner of NovaLash, a global distributor of eyelash extension products, if you see lashes that say “synthetic polyester fiber,” these are made to be very flexible and light with a slight sheen. “These are the lightest of all extensions and give a soft, feathery look. Lashes that are marketed as “silk” are typically darker in appearance and create more of a dramatic look. And lastly, “polyester fiber lashes” are the heaviest of the Korean PBT varieties, and will therefore create a bold look.


“Mink lashes are made from animal hair and are not widely used in the U.S. industry,” says Nguyen. “While they are soft and silky, they do not hold a curl very well. They can also cause reactions due to allergies and sensitivities. Additionally, they are obviously not vegan or cruelty-free.” They are more expensive, too, and therefore the lash extension services are more expensive as well.

What to Expect at a Lash Extension Appointment

“First, a lash stylist will consult with you to find out your preferences and assess your distinctive eye shape and skin tone,” says Clementina Richardson, a lash technician, lash expert and founder of Envious Lashes in New York. “They will also determine the quality of your natural lashes. Then together, you will pick a lash style. Lashes come in various lengths, curvatures and widths, which are carefully selected to create a custom look for each client.” The lash technician will apply your lashes while you’re laying down with your eyes closed. If you don’t feel like talking during your appointment, let them know you prefer not to and would rather just relax. Or, let them know you’ll be listening to headphones in case they need to ask you a question during the treatment. Then, each faux lash extension is glued to a natural lash hair with glue.

The Lash Extension Adhesive

There isn’t a universal adhesive used at all salons. So, before your appointment, ask what kind of adhesive the salon uses. “You only want American-made medical- or surgical-grade glue that is formaldehyde-free and FDA-approved,” says Merszei. “Exposure to formaldehyde in the eye area can cause swelling and puffiness.” Sometimes even safe, formaldehyde-free glue can cause irritation. In these cases, stylists can switch you to a hypoallergenic version, although some people complain it doesn’t hold as well. Or, the glue might be clear instead of black, and slightly visible on the lash line.

“Almost all of the adhesives used for professional salon extensions are cyanoacrylate-based,” Nguyen explains. “This means that they will cure when they come into contact with the moisture in the air. The rate at which they cure [the chemical process of creating the bond] will depend on the concentration and other additives to the formulation. For example, some adhesives contain carbon black, which is used to darken the color of the adhesive. The environment of the lashing workspace also plays a role in how fast the adhesive cures.”

How to Choose a Lash Technician

Another important factor to consider when getting lash extensions is the lash stylist you choose to apply them. “Safety should be your number-one concern,” says Richardson. “Finding someone who is certified to apply the lashes is a must. Depending on the state, the stylist also needs to be licensed, not just certified. Do your research to find the right lash stylist in your city.” 

Nguyen agrees, saying not all lash techs have the same experience, training or knowledge. “Make sure your lash tech has high-quality photos of their work on Instagram so you can verify their skill level,” she says. “This is especially important if you are seeking a highly specialized lash look that not every tech is well-versed in. Also check to see if they have listed their prices, credentials, products used, and salon policies to ensure they are a good fit.”

It may be tempting to choose a technician offering a steep discount, but Richardson cautions choosing a bargain over a safe, quality experience. “Avoid going to any lash stylist that can see you at that exact moment, or who is offering a lower rate. I have seen way too many improper applications and damaged lashes over the course of my career. Even if you need to wait one month to see the right lash stylist, trust me it’s worth the wait!”

How Long Do Lash Extensions Last?

With proper care, lash extensions can last up to six weeks before they all shed. But, most people get them filled every two or three weeks to keep them full. “Lash extensions can fall of or shed in different ways,” says Richardson. “Typically, your natural lashes grow to maturity and the lash extensions shed with them during their normal shedding process.”

A common concern is that lash extensions ruin your natural lashes, but Richardson says this is not the case. “This only happens as the result of improper application or the stylist not selecting the correct type of lash.” To keep your natural lashes healthy while wearing falsies, apply a conditioning serum to your lash line each night. We like Grande Cosmetics GrandeLASH-MD ($65), RevitaLash Advanced Eyelash Conditioner and NULASTIN Lash Follicle Enhancing Serum.

How to Care for Your Lash Extensions

  • Avoid steam and getting your lashes wet for the first 48 hours. “This is very important,” says Richardson. “You can of course wash your face and take a shower, but just make sure that no water touches your lashes.”
  • “To keep your lashes looking as good as they did day one, it’s crucial to wash your lashes with a lash cleanser daily!” says Nguyen. “Not washing them creates the perfect breeding ground for lash mites!” However, only use oil-free cleansers and makeup removers around your eyes that are specially formulated to be safe for eyelash extensions. “Other products may contain ingredients that can weaken the bond of your extensions and cause them to shed prematurely,” adds Richardson. “If you are making an investment in extensions in the first place, you surely don’t want to see them go to waste.”
  • Try not to wear mascara while you have on lash extensions. But if you must, Richardson recommends using a water-soluble formula only. “Wearing mascara will shorten the lifespan of your lashes.”
  • Don’t pick at your lashes, or excessively touch them. “Picking at your lashes can cause premature fall out,” says Nguyen. “It can also lead to your natural lashes being picked out, which will result in a sparse lash line.”
  • “Never use a mechanical eyelash curler,” Richardson says. “If the curl of your extensions is starting to fall, use a heated eyelash curler like Envious Lashes Heated Curler to gently lift them.”
  • “Brushing your extensions once a day helps keep them fluffy and beautiful until your next fill,” says Nguyen. You can use a spoolie brush to gently brush them.
  • Don’t sleep face down. “Try to sleep on your back or side,” says Richardson. “Also use a silk pillowcase if you can, which is gentler on your lashes, and your hair.”

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