A: Such an innocent question. It seems so simple: Gloss, glaze, which is which? But you, dear reader, have sent me down the rabbit hole. Marie Leppard, senior colorist at the Julien Farel Salon in New York City (who gives me my highlights), told me authoritatively that a gloss is a bit more permanent than a glaze. It adds shine and adjusts the tone (say, if your highlights are too bright or brassy, a gloss will subdue them), she explains. A gloss penetrates the hair's cuticle, so it lasts two to four weeks. A glaze, on the other hand, simply coats the shaft with shine and semipermanent color; it's like putting a top coat of polish on your hair, and it lasts a week or two. But here's the problem: Haircare companies use "gloss" and "glaze" interchangeably. According to cosmetic chemist Mort Westman—our ultimate resource for clarification about all things confusing in the beauty business—originally, a glaze added shine and deposited semipermanent color, and a gloss added only shine, but the word "gloss" was added to dye products because it's appealing to people who are coloring their hair.
Bottom line: If you want just shine, look for a "clear" gloss or glaze (like Frédéric Fekkai Salon Glaze Clear Shine Rinse, $28). If you're looking to boost your color or bump up your highlights, choose a gloss or glaze with "semipermanent" color (like John Frieda Luminous Color Glaze, $10).