"If you leave your color on for too long, there is potential for extra deposit of pigment to occur. You can't make your hair too light by leaving a tint color on too long (unless you're bleaching), but it can make your hair darker than intended," says Tardo.
If you leave permanent hair dye on your hair for too long, your hair will turn darker than expected because the process of oxidation is continuing and changing the tone of your locks. Brittle hair tends to darken more as well due to its weak structure, allowing for quicker absorption.
Leaving boxed hair dye on for hours longer or every overnight than the manufacturer's instructions could result in an irritated scalp. It might also stain your scalp or skin adjacent to your hairline. Staining your scalp or skin is just one potential issue.
Wait 20 minutes for the roots to process, then it's time to refresh your ends. “Take sections of your hair, from the top, and apply the colour through the lengths of your hair. When you feel that you've saturated all the ends, leave it for ten minutes, and then shampoo,” Josh advises.
Before that, let's answer the question of what would happen if you left hair dye in for longer than you're supposed to. Typically, what happens is that your hair becomes a shade or two darker than it's supposed to be. Leaving the hair dye in for longer allows the dye to set and create a stronger effect.
"After having your hair colored, wait a full 72 hours before shampooing," says Eva Scrivo, a hairstylist in New York City. "It takes up to three days for the cuticle layer to fully close, which traps the color molecule, allowing for longer lasting hair color."
While there is conflicting information on how to long to wait to wash your hair after coloring it, most experts say that you should wait about 24–48 hours after dyeing your hair to wash it, allowing time for the hair color set and for your hair's cuticle layer to close without risking any color fading.
Salons wash hair after coloring because they need to prepare your hair for the next treatment, which is important if you are planning a straightening or curling treatment directly after your hair has been dyed.
After shampooing, it's important to follow up with a conditioner. This is because shampoo - and yes, dye - can sometimes strip away natural oils that your hair needs to stay healthy. Conditioner helps to replenish these lost oils, as well as add extra moisture to your locks.
Reasons why hairdressers hate box dye is that it usually contains harsh chemicals which can easily cause damage, discolorations and irritation if used improperly. Some box dyes are known to contain low-grade ingredients that don't develop the same results as chemical-based products applied by a professional.
Hair color needs at least 48 hours to settle into the hair strands. So, if you wash your hair 24 hours after highlighting, the color will quickly wash away and become dull.
During the first 48 hours after a color service, the pigments of the salon color are still settling—meaning if you shampoo your hair too soon after an appointment, it can cause your hue to fade quicker.
Applying hair color before a haircut makes it so much easier to section while coloring, prevents color overlapping from one section to another, and gives you a great final cut and color.
More often than not a colour which won't hold is the result of a lack of treatment. However, in the case of home colouring, the problem can often be due to the colouring process. Either the application isn't even, the waiting time is too short or you aren't using the right product for the desired effect.
We often get the question: how long do you have to let the hair dye sit before rinsing it out? The answer is, you always have to let the dye sit for at least 35 minutes from the moment you've finished applying all of the dye. After 45 minutes the dye loses it's effect so it's no use letting it sit any longer.
Now, hair dyes are made with more gentle formulas. As a result, colorists recommend washing the hair to remove the grime before coloring, because the excess buildup might result in an uneven dye job. The best way is to wait for at least 24 hours after washing before dyeing your hair.
To keep your new hair color vivid and bright, we advise that you wash your hair with cold water (as cold as is bearable). Cold water keeps the hair cuticles closed and therefore stops the color running out and fading too soon. Warm water is the enemy!
“A big trick is always using hot water when you shower, because it's opening up the cuticle and getting that dye to fade quicker,” she says. “Most brands and professionals will recommend cold water to keep the color vibrant, but for fading definitely use warm [or] hot water.”
Gutkin says to begin applying dye at the roots first, “since the roots need the most color and processing time,” and Rez advises really saturating them with color. “Then, apply dye from the back to the front to ensure the dye is sitting on the back of your hair the longest,” Gutkin says.
Shampoo Your Color-Treated Hair Less Frequently
– To prevent water from washing away your vibrant color, the answer is simple: Wash your hair less often. To retain those natural oils that help condition your color-treated hair, shampoo just two or three times per week, and never more than every other day.
When To Use Purple Shampoo After Bleaching? Avoid washing your mane for the first 48 to 72 hours after bleaching it. This is to give your hair enough time to seal in its new color. If you waited 72 hours before washing your hair after it was bleached, you could use the purple shampoo the next time you shower.
"After you dye your hair, don't wash it for at least two days because the hair is still sensitive and therefore will be more like to fade faster," says Sergio Pattirane, a hairstylist at Rob Peetoom in New York City. "We recommend waiting to wash it so that the color stay fresh and longer."
Leo Izquierdo, a colorist at New York's IGK Salon, agrees, adding that hot water will lift the outer layer of hair color and cause the color to fade. “Instead, rinse with cold or lukewarm water, as it will help seal up the cuticle and lock in your fresh color,” says Cleveland.