Q: My hair is dull; I’d like to try a gloss or a glaze. What’s the difference?

Such an innocent question. It seems so simple: Gloss, glaze, which is which? Well, start here: 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). 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. 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).