Does Hair Dye Color Matter When Deciding Whether or Not to Wash It?

While your hair should be clean for all hair coloring services, how clean may depend on the color you’re going for. In most cases, having freshly washed strands is ideal—as Moore says, “hair color needs the path of least resistance” for the most seamless end results. This is especially true if you’re using a semi-permanent hair color, like a hair gloss. According to Moore, these gentler formulas may have a harder time breaking through oil and product build-up—so if you want a seamless color, a thorough shampooing prior to your appointment is key.

There are, however, exceptions. If you have a sensitive scalp and are getting a root touch-up—or are having bleach applied directly to your scalp—second-day hair is best, Moore says. The slight “barrier” provided by your scalp’s natural oils can help prevent your scalp from tingling or feeling irritated while your color is processing. If you’re unsure if hair dye will irritate your scalp, talk to your dermatologist and hair colorist before your appointment.

Is It Best To Skip Washes Before Bleaching?

Bleach can be harsh on your scalp and strands, so it’s not surprising that people often opt to skip a few washes before bleaching their hair. According to Moore, that’s not the best approach. You should still wash your hair before bleaching it—just perhaps not immediately before.

“If your hair is too dirty, it will not lift enough,” Moore says. “And believe me, [a single] on-scalp bleach application is enough for one day.” She suggests lathering up the day before bleaching your hair for the best results. “The stimulation on your head (scratching, scrubbing, etc.) from shampooing could cause your head to be tingly or itchy when the product is applied,” she explains. If your scalp is extremely sensitive, you can wash your hair up to two days before your appointment.

Can Hair Products Interfere With the Coloring Process?

“Styling products and sprays can definitely create barriers between the hair and the color product,” Moore says. So when it comes to styling your hair before an appointment, a less-is-more approach is best. A bit of product on the mids and ends of the hair isn’t a big deal, but avoid applying oil or gel to your scalp (especially before a root application), as doing so can result in a patchy, uneven color. Similarly, use hot tools with care. Heat can damage the hair and make it more porous, Moore explains. And damaged hair “will absorb and react to color differently than healthy hair.” If your hair is super damaged, you may want to consult with your colorist before committing to that bleach session or intense all-over dye job.