Beauty Hair The One Thing You Need To Do Before Getting Highlights, According to a Colorist A celebrity hair colorist advises on whether hair can be too greasy to dye. By Victoria Moorhouse Victoria Moorhouse Instagram Website Victoria Moorhouse is a writer, editor, and consultant based in Brooklyn, New York who focuses on beauty, fitness, and health. Victoria was previously the Senior Beauty Editor at InStyle.com and a Senior Editor at POPSUGAR. Her work can also be found in notable publications such as Shape.com, The Zoe Report, Forbes.com, and Well+Good. She graduated from The College of New Jersey with a Bachelor's Degree in Journalism and Professional Writing. InStyle's editorial guidelines Updated on August 14, 2022 @ 11:00AM Pin Share Tweet Email Photo: Peter White / Getty Images It's been five or more days since you've washed your hair and the proof is in your oily roots, but you also have a much-needed appointment with your colorist after work. If you're like me, there's a solid chance that you skipped on the shampoo and pressed snooze three more times knowing that you'd get a wash later. It seems like a harmless, time-saving hack, but going to the salon with oily hair could be a huge mistake. According to celebrity hair colorist Matt Rez, overly greasy hair is more difficult to highlight, and can even get in the way of covering up grays. "When hair is greasy, it has a lot of build-up, and it is very hard to weave precisely," Rez says. "Unless you are getting a solid bleach blonde or being lifted with a strong permanent color, I prefer clean hair [to dye]." This, of course, brings up the question of the actual definition of dirty hair. Is it second-day hair? Is it hair that hasn't been shampooed in a week? 11 Tips to Keep in Mind Before Dyeing Your Own Hair at Home Rez notes it's less about the last time you washed your hair (because that is really situational) and more about how the hair looks, feels, and even smells. He considers hair too oily or greasy to be highlighted when you can see the natural scalp oil glistening at the roots, when there is noticeable scalp buildup and dandruff, or if there's a slight odor. Coinage: Cost of Getting Your Hair Dyed With that being said, you probably don't have to tell your colorist the last time you washed your hair because they'll likely be able to figure it out. And if they don't ask, Rez says they're not worried about it. So if you can't remember the last time you washed your hair and you've resorted to a slicked-back ponytail, be sure to fit in a shampoo session before rolling up to the salon.