What does size mean anyway? There are two sizes that are relevant to skin care. One is the molecular weight and the other one is particle size. Molecular weight refers to the weight of one molecule expressed in daltons. On the other hand, particle size refers to the width of a particle expressed in some unit of length (usually micrometers or nanometers). For example, the molecular weight of water is 18 daltons, and the particle size of one molecule of water is 0.27 nanometers.

In skin care, both sizing parameters are used. For active ingredients such as alpha hydroxy acids and hyaluronic acids, molecular weight is a much more relevant number. When talking about powders, especially sunscreen filters like zinc oxide and titanium dioxide, it makes much more sense to talk about their particle size. Of course, size is only one parameter, so one must consider other examples of when size matters in skincare.

Gloria Lu studied chemical engineering with a focus on renewable energies at Cornell University. Interestingly enough, Lu did not have an interest in the beauty industry until landing a summer internship at L’Oréal. During that summer, she fell in love with the fast-paced environment and product development process. That internship transitioned into a full-time job with the skin care laboratory, specializing in clinical products with high levels of active ingredients. Her cubicle neighbor was Victoria Fu, and the rest is history. After leaving L’Oréal together to launch Chemist Confessions, the women established a large following on social media through educational and creative content, in addition to creating a blog and launching their own skin care line. Notably, they recently authored a book, “Skincare Decoded.”

While in school at UC San Diego, Victoria Fu studied chemical engineering and was part of a research team that studied nano-carrier therapeutics that focused on topical therapies for acne. Having struggled with acne all her life, Fu felt like this was a great fit for her at the time but feared a future in pharmacy would limit her creativity. After completing her masters, she landed a job in the L’Oréal skin care laboratory. During her four years as a skin care chemist, Fu worked more upstream in antiaging, which included anything from sunscreen to antiaging serums.