What are cosmetics made of? Where did they come up with that shade or that scent? How did brazil nut oil and jojoba end up in your shampoo and conditioner? What keeps face cream from becoming "toxic" in the jar?
As a cosmetic chemist, you find the answers to these kinds of questions. A cosmetic chemist spends a lot of time in the lab, trying new things, mixing, researching, testing, and concocting the exact formulas to make the products we buy useful, safe, and appealing.