Thanks to chemistry, the products we use to clean and style our hair have evolved over decades — even centuries. How do hairsprays protect your hair while keeping it flexible and light? How do shampoos work, and why are some people choosing to dump the lather altogether? This week, “Ms. Beautyphile” Trina Espinoza and Lex Fleming from “Made U Look” join us in the New York City YouTube Space to explain the science behind hair care.