When Roselin Rosario-Meléndez graduated from her doctorate degree from Rutgers University, she had an offer on the table from L’Oreal. The makeup giant wanted Rosario to come work for them, but the Puerto Rican chemist said no. 

“After a while I wanted to have a closer relationship with consumers,” Rosario recalls. It was then that she applied for a job at L’Oreal, where she works as an Associate Principal Scientist in the face makeup and hybrids department, developing products and formulas for L’Oreal’s wide ranging set of brands, like Maybelline, L’Oreal Paris, and NYX. 

Born in Aibonito, Puerto Rico, Rosario has led a 12-year-long career as a scientist, working with companies like Merck and Ingredion, after graduating from the University of Puerto Rico’s Cayey campus. She’s the only person in her family to go into a career in STEM, and she credits mentorship as one of the sources of her success, which is why she pays it forward constantly with her own mentees. 

“I’ve had a lot of success, but I don’t want to hold on to that,” she says. “I want to give it back to other women who want to be where I am.”

Images courtesy of L’Oreal via Instagram.

Shop Maybelline’s SuperStay Ink Crayon ($8) and Matte Ink ($8).

Rosario’s specialty as a scientist is polymers, macromolecules used in many products, a commonly known product made of polymers is plastic. But, at L’Oreal, she uses polymers to create makeup formulas that resist heat, oil, and movement to stay put all day.

This is how she created Maybelline’s ultra famous SuperStay Matte Ink lipstick formula, a longwearing and highly-pigmented product that promises to stay on your lips for up to 16 hours. The line offers 40 colors in a liquid lipstick formula that’s one of the best-selling and most popular from the brand. Rosario also worked on Maybelline’s SuperStay Ink Crayon, which is a sister product to the Matte Ink liquid lipstick. 

“Obviously, there were a lot of failed experiments,” Rosario says. “It’s all part of it.”

We chatted with Rosario about her career as a scientist, being a Latina in STEM, and what it’s like to create one of the best lipsticks of our times. 

Emperifollá: Were you always interested in beauty and science? 

Roselin Rosario: I was always interested in both but in separate ways. I didn’t know the connection between the two. I’ve always liked makeup up since I was a kid. Obviously, I was not allowed to use any of it, but I was always curious about it. It wasn’t until grad school that I was able to make that connection, of being a scientist and use that knowledge to create makeup formulas and products. 

Eá: What was it like to immerse yourself in the L’Oreal world? 

RR: It’s funny because I didn’t use lipstick when I started there. Ironically, of all the cosmetics out there that I actually use, I started working in the lipstick department. Even now, it’s not what I use the most. So one of the first few things I did was try as many lipstick formulas as I could. I had to learn about all the different types of lipsticks– liquids, lip gloss, sticks, lip balms. That was all part of starting out because I needed to understand what was already on the market. 

I did it so much that I can now read a lipstick’s ingredients and know what it’ll look and feel like without actually trying it on. 

Eá: That sounds really fun. 

RR: Yes, but it’s also a lot of work because after that comes the process of taking these ingredients, learning how to combine them, understanding what temperature. You can do anything in the lab, you can invent whatever. But you also have to think about mass production, how is this product going to make it from the lab to the market? Obviously, there were a lot of failed experiments, it’s all part of it. 

Eá: You created the SuperStay lipstick formula, how was that process?

RR: Most of our projects are directed by the company. There is room for us to bring ideas to the table, but I was new at the time. The objective was to create a lipstick that was just one product, but that was longwearing and comfortable. I used a technology that the company had already invented and patented and incorporated it in the formula with other ingredients to achieve our objective.

I was the first person to try them, of course, to know if it was going in the right direction. You can always try them on certain substrates or on the arm, but it’s never the same. I quickly realized that I had a product unlike anything else that was out there.

Eá: Can you tease any other products that you’ve worked on recently?

RR: My first project in the face makeup innovation team was scaling up a product and getting it ready to hit the market. I worked on understanding the physical and chemical properties of the product. It’s coming out this summer.

Eá: You also do a lot of mentorship work, why is it so important to you? 

RR: Numbers don’t lie. There is a lack of Latinas in STEM. The cosmetics industry does attract a lot of women, but even then the proportions are off. It’s a combination between the lack of opportunities for Latinas in general, but also a lack of effort from recruiters. In all industries there is a lot of emphasis right now from a diversity and inclusion standpoint, but that wasn’t a priority in the past. Even when I’ve been recruiting, I wouldn’t see a single resumé from a Latina. That was hard to believe, considering it was a role to develop makeup.

Eá: How does your Puerto Rican heritage inform your work at L’Oreal?

RR: It does influence me a lot. In the past couple of years, there has been a huge push to expand shade ranges. A launch has to have at least 40 shades to be inclusive. I always bring that perspective in as a Latina. I’ve also worked with brands on translating product information to Spanish, making sure the technical part is translated correctly, and that they are approaching consumers the right way. Even when they have consultants, it’s important to note when things are off or might not make sense for our community.

As a scientist making face makeup, it’s important to always have in mind how different ingredients behave on different skin tones. I always pause to test them and have a global vision for the products I make. In the end, it’ll make us more successful.

Eá: What makes you feel emperifollá? 

RR: For me, it’s about getting dressed and dolled up for oneself. I feel fine with a bata and no makeup at home. But getting emperifollá is about giving myself some love and taking them time to play with makeup, choosing an outfit. In Puerto Rico, you never go out without getting emperifollá. It’s something I’ve kept going for myself, even in the lab. It’s self-respect. 

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