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.
There are a few reasons the dye isn't taking; 1) It could be that your hair is naturally resistant to bleach 2) the developer may not be strong enough 3) you may not be leaving the dye in long enough. 4) direct dyes usually require hair to be lifted to a level 10 blonde or higher for best results.
If your hair floats, it has low porosity, which means it will have a more difficult time both taking in and holding onto color. If your hair sinks, it has high porosity, which means it will take color but may not hold onto it too long.
Heat styling, hot water, sun exposure, chlorine and salt water can strip the color molecules out. Hair damned from chemical processes can have a hard time holding color because the bonds are broken.
To preserve your hue, you'll need to pamper your hair a bit. That means adding extra protection from everyday stressors like water, shampoo, heat and sun, as well as nourishing hair with plenty of hydration. Color maintenance takes more attention and care, but it's worth it to maximize those beautiful results.
Over washing is a major factor – shampooing too often strips your hair of natural oils and colour pigments, leaving it looking dull. Sun exposure is another sneaky offender, as UV rays break down hair dye molecules, leading to premature fading.
The Science Behind Hair Color Absorption
If it's too closed or damaged, dye can't penetrate well. Healthy hair with an open cuticle layer will soak up color better, giving you that vibrant look. The pH level and the porosity of your hair also affect how well it takes color.
Pigment loss occurs naturally in hair as we age. Along with the changes in pigmentation, grey hairs can also undergo structural changes Grey hair is often also coarser. The outer cuticle layer of greys can be more tightly packed and layered, making them resistant to colour absorption.
Red hair is notoriously difficult when it comes to upkeep. While it's the hardest color to fully strip from your hair, it's also the first to fade, often lightening drastically within the first few washes. So unless you're wanting to touch-up your own color at home, it would be wise to skip the scarlet shades.
Brittle, split, and dry hair won't take hair dye the same way healthy hair does. If your hair is damaged, the dye's chemicals will penetrate the hair cuticles differently, and you may end up with patchy or faded color. Prep your hair before you color to make sure all your strands are as healthy as they can be!
It could be that your hair is resistant to tint, especially when the hair texture has changed as a result of going white. But also it could be that by going lighter, either all over, or by introducing (subtle) highlights you would not see the regrowth strip quite as quickly as if it were lighter.
You Have Damaged Hair
Unfortunately, dry and damaged strands don't hold onto color well. Damaged hair has a loose cuticle, with lots of holes, tears, and gaps along its surface. Although these gaps make it easy for dye pigments to enter your strands, your hair has no way of holding onto them.
The vinegar actually helps the hair dye to remain bonded to the hair, according to my awesome stylist Viviane of Marina Beach Hair.
Our favorite color-depositing conditioner is the dpHue Gloss+ thanks to its wide range of shades, easy application, and ability to soften and hydrate hair. For a clear gloss that adds shine to any hair color, we recommend the Pureology Color Fanatic Top Coat + Sheer.
Final answer: Hair that is resistant to color and has a tight cuticle is characterized as having low porosity. Porosity defines the hair's ability to absorb and hold moisture, with low porosity hair being more resistant to chemical treatments.
"Specifically, oestrogen, progesterone and cortisol can all play a part in the changes to hair colour – but oestrogen is the main factor in determining the higher content of melanins called eumelanin and pheomelanin in female hair.
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.
Low porosity hair doesn't absorb product
Because the cuticles are so tight, products including creams, oils and water-based formulas, tend to sit on top of the hair instead of being absorbed.
As a general rule of thumb, darker colors tend to stay on the hair for longer. So, if you're adding lowlights, a root shadow or all-over depth, the shade will offer more mileage than, for example, light blondes, light browns or light reds. The same goes for pastel colors versus rainbow colors.
It could be that the hair dye you were using has put a layer around your hair that prevents the new dye from adhering well to your hair. This is especially the case when using henna, a reason why other hair dyes don't take.