Leaving a permanent or semi-permanent dye in for too long can damage your hair and strip away essential moisture. The longer you leave a permanent or semi-permanent dye in, the deeper it penetrates into your hair cuticles and can cause irrevocable damage.
"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.
Direct dyes don't use developer, so it's not like the chemical reaction caused by the developer can stop. Also, these kind of dyes do no damage to the hair and are often even loaded with moisturizing or conditioning ingredients, so leaving them on overnight will not be a problem.
Permanent hair dye penetrates all the way through your hair follicles and contains strong chemicals. Leaving those strong chemicals in for too long can damage your hair and affect how fragile or strong it is. It can also make your hair harder to change back to its original color or to dye a new color.
Over time, and with repeated colouring sessions, these changes in the structure of your hair will leave it weaker and more prone to breakage. The more hair is dye damaged, the less the colour holds. That's why it's so important to prioritise repair if you colour your hair.
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.
The reality is, the more often you color your hair, the greater the potential for hair shedding. Hair dye does not stop or even slow down hair growth, but it can cause hair loss by damaging the color-treated hair.
To summarize, you should leave hair dye in your hair for a minimum of 30 minutes and a maximum of 45. Avoid leaving the hair dye in too long because this may cause your hair to become dry and brittle.
Timing. Timing is 30 minutes for standard color application; 45 minutes for maximum gray coverage and for high-lift shades. Typically, with permanent color, the first 15 minutes provide time for the peroxide and ammonia to open the cuticle and penetrate into the cortex to lighten natural pigment.
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.
After you dye your hair, wait two days before shampooing. If you can double that to four days, the result will be even better. That's because the dye will have enough time to set. Wash your hair less often if you can.
"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."
Make sure that you give your hair enough time to dry before bedtime. If you must go to sleep while your hair is still wet, braid it first. Don't pull your hair into a bun or ponytail before going to sleep, even when it is dry. This will damage your hair further.
If this is the first time you've dyed your locks, you might need to adjust your washing routine. This is to make sure you're not over-washing your hair. Hair that's dyed with a lot of pigment can look more faded the more you wash it.
The main cause of hair color appearing progressively darker over repeated applications is in the application of the dye itself. That is, many people make the mistake of coloring their entire head of hair each time they color. Not only do you not need to do this, you don't want to do this, either.
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.
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.
Coloring your hair in a salon by a professional stylist on average can take anywhere from 2 to 6 hours, and can even extend to as long as 8 hours depending on your hair's condition, length, natural color, and intricacy of service.
Because the outer cuticle has been penetrated by the dye, the natural oil of your hair, known as sebum, doesn't travel down the strand.
This is because the dye may affect proteins and lipids present in the hair, which contribute to hair health. Changes to the inner and outer structure of the hair shaft can damage hair, making it fragile and prone to breakage, which could eventually result in thinning hair or hair loss in areas.
Since semi permanent hair color simply coats the strand of your hair, it results in lesser damage. If you are someone who colors their hair to cover their greys, this type of hair color is perfect for you. Even with regular usage, non-permanent hair color doesn't damage your hair as much as permanent hair color.
“Does box dye damage hair?” Yes! Box dye is not formulated to the same standard as professional hair colour. Salon hair colour costs more because it is better quality. It doesn't contain so many harsh ingredients and often works to protect your hair as it colours.
Is boxed hair color safe to use? You may have heard that drugstore hair dyes are inferior or harsher than the dyes used in salons, but that generally isn't true. The way hair dyes function and the ingredients used to make them do not differ between the drugstore dyes and the salon dyes.
The color is usually easy to mix with little to no measuring, though, it comes with no options to alter the pigmentation. The dye itself is typically a more concentrated formulation than salon hair color because the color has to be strong enough to work on anyone's hair.