With a boom in face masks in the last few seasons, that old-time ritual of putting on a face mask in the privacy of oneโ€™s home is seriously passรฉ. โ€œMaskingโ€ is well out in the open.

In fact, there is even a beauty phenomenon called mask bingeing. โ€œThatโ€™s when people put on several different masks in a row to treat whatever they want,โ€ said Lev Glazman, a founder of the Fresh skin-care line.

Mr. Glazman credits millennials on Instagram for the proliferation of face mask products. โ€œMillennials are triggering something in beauty, and then the other groups are looking and maybe following,โ€ he said, adding that he has learned a lot from his daughters, ages 18 and 22.