How To Dye Blonde Hair Dark Again, Because It's Not As Easy As It Sounds

Switching up your hair color is one of the biggest ways to update your look, but there's a chance, a few months down the road, you might change your mind yet again. For those who have gone lighter, you may want to learn how to dye blonde hair dark again. But the process can be tricky, and you don't want to end up with damaged hair, especially when there are ways to avoid it.

If you've gone blonde, you know it can take a long time, a lot of money, and many salon trips, so you might be a little concerned about performing the task in reverse. But you're not alone: Plenty of celebrities have transitioned from blonde to dark without damaging their hair. Some are even going back to their roots — Khloe Kardashian recently ditched her signature blonde for a shade closer to her natural brunette hue, and her sister Kendall Jenner went blonde for a few days for 2019's London Fashion Week before returning to her regular color. Emily Ratajkowski went bleach blonde in June but has since gone back to brunette.

If these celebrities can switch their hair color from light to dark, why can't anyone? Bustle spoke with hairstylists to find out the safest and most effective ways to return your blonde to brunette.

First: Assess Your Hair's Condition

First up, assess how healthy your hair is and how dark you want to go. Kathy Debski, colorist at SPACE by Alex Brown in Chicago, says that means checking for visible damage, like breakage, as well as a dull or lifeless appearance. "This usually means that the cuticle — outer layer — is compromised," she says. "Usually, the hair is frizzy at the ends and doesn’t look supple."

Nine Zero One Los Angeles stylist Sarah Klein also emphasizes assessing your hair before coloring it, but adds that it's usually easier to go darker instead of lighter. "Typically most hair types can handle it," she says, "but it’s always good to check the porosity and elasticity of the hair and do treatments before any color service."

Porosity, in short, is how well your hair absorbs and retains moisture. "The more porous the hair is, the easier it is to absorb any kind of products," Debski says. "However, with highly porous hair, the cuticle is more open so it's harder to keep moisture in. This is important to know when coloring so the color adheres evenly." Debski adds that a pre-color protein treatment can help keep your hair's porosity level even throughout and, in turn, help your color absorb evenly.

After you take stock of your hair's health, you need to figure out how much darker you want to go. Debski and Klein say the easiest route is to take the color as close to your natural shade as possible — it's low maintenance, and you'll avoid too many salon visits.

Finally, hair texture plays a role in how your dye the hair, although not necessarily how dark you can go. "Curly hair tends to have a rougher cuticle, which makes it porous and it will absorb the color quicker," Debski says. "When coloring a curly texture, you want to formulate on the lighter and warmer side so it doesn’t deposit too dark or muddy. With hair that is on the straighter side, the cuticle is a bit more closed, so the color has to have more time to penetrate the cuticle."

Next, You Have To 'Fill' The Hair

When it comes to the actual coloring process, "filling" the hair is the most crucial step, regardless of texture or the color you're aiming to achieve.

Debski describes filling as "a process where the warm pigments are redeposited into the hair so the new brown shade can truly stick. Usually, this is done in a two- to three-step process, each time going a little bit warmer and darker until you reach the desired undertone."

Klein says this step is crucial to achieving a deeper shade that doesn't turn ashy, muddy, or dull. "Once the hair has been lifted to pale yellow, it’s been stripped of the necessary underlying pigments that are needed to go back to the darker levels," she says. "Therefore you must 'fill' the hair first with orange, golds, coppers, and sometimes red, depending on what [level of darkness] you're trying to achieve, before putting the all-over color on top."

The blonder your hair is, the longer the filling process will take — so if you're going from platinum back to brunette, expect to spend a while in the salon.

The True Color Comes Last

Once the hair has been filled and is totally dry, you can move on to the final deeper color. Then, the brown shade is applied to the root and pulled through to the base of the hair. Debski says to process for the amount of time recommended by the product. Afterward, you can apply a glaze to lock in the color.

Klein also suggests adding in additional colors to create dimension. "I still like to add gold or copper to my overall toners," she says, "to keep the hair reflective and shiny and assure that it won’t go dull."

FYI: DIYs Need To Go Through The Same Steps

If you're going to attempt the process yourself, Honey Artists hairstylist Tyler Colton says you still need to go through the process of filling the hair at home. This means using multiple shades of color. He says you'll first need to use a demi-permanent color (a color that wraps around the shaft and washes away, unlike a permanent color) in a copper-gold shade. Let that sit for 10 minutes, then rinse or lightly shampoo. Colton warns that the color will be "bright and scary looking," but your next shade will fix that.

If you're going to a medium or dark brunette, he says for your next step, "You will use a [medium brown] also in a demi-permanent color. Process the entire 20 minutes before shampooing. Remember, this will cover your blonde back to a solid looking brunette. If you are looking for more dimension, highlights, or ombre, then you should see a professional colorist!"

Aftercare Is A Must

You want to make sure you maintain your hair color, and the right products go a long way. Color-safe shampoos and conditioners will help protect the new shade. Klein says these should be sulfate-free, and she also recommends getting a shower filter to remove minerals and hard metals so they don't affect the hair. She also recommends using a heat protectant, which will prevent fading if you use hot tools.