Chemistry know-how matters. To count the ways, we talked to Cassandra Celestin (www.thehairchemist.com), who holds a cosmetology license and a master’s degree in cosmetic chemistry. She’s worked with companies such as L’Oreal, Shiseido, Clairol, Dark and Lovely, Vidal Sassoon, to name a few, and currently freelances in Miami Beach.

Q: How did your chemistry degree help when you worked in a salon?

A: I understood how products worked on hair both structurally and topically. It also helped me choose the right brand for specific results. Because of certain raw materials, one brand of blonde translates into more pink while another is more golden. The experience of formulating helped me correct color.

Q: What’s the most interesting project you worked on as a chemist?

A: We were asked to develop a hair color you could flatiron into the hair. The problem was that it left residue. The company decided there was no market for it—they felt services like Japanese thermal straightening would become too trendy.

Q: What’s the newest trend in color chemistry?

A: Companies are using a lot of different raw materials to improve the hair’s fiber and manage free radicals.

Q: What do colorists misunderstand about chemistry?

A: They don’t know precisely how color works in the hair. Once, the top colorist at a company didn’t understand why a semipermanent color used in foil after bleaching left zebra stripes from time to time. It came down to how semipermanent color deposits and then gets disturbed with several foil folds. The resolution was to avoid folding foils and use a filler. Colorists have to ask more questions about how and why a product does what it does.

Q: What would you like to see developed next?

A: More metallic tones. Not chrome or titanium hair color, but iridescent, luminous shades that work with what’s happening in fashion.