Hair color is a fabulous way to change your style and us women have been changing our hair color for hundreds of years. Romans applied colored paste with lime to their locks to change the color but in 1907 L’Oreal’s Eugene Schueller invented the reliable synthetic hair dyes we know today and we have been going crazy for color ever since.
Coloring your hair is achieved in two ways: either bleaching or staining.
Bleaching To Go Lighter
If you have darker hair and want to go lighter, you have to remove the color already in your hair. This is commonly done using hydrogen peroxide which reacts with melanin (the color molecules in your hair) rendering it permanently colorless.
How much color is removed depends on the strength of the peroxide used and whether an alkalizing agent like ammonia is used. Ammonia is an alkaline that opens the cuticles to allow the bleach into the hair shaft and react with even more melanin.
During the application of the alkaline ammonia, hair swells which weakens it substantially. This is why black women who relax their hair are advised against coloring their hair as well.
Hair relaxers are also alkaline so relaxed hair has already weakened from the swelling during the relaxing process. Coloring on top of that would irreparably damage the hair fiber and intense breakage becomes inevitable after that.
If virgin hair is colored with an alkalizing agent, although it won’t change the natural structure of the hair (curls remain the same), the chemical process may leave the hair weaker than it was before due to loss of protein during the coloring process. This is why a color stylist will advise you against going too light if your natural hair color is very dark brown to black.
Once the hair is bleached, it is then stained with the coloring agent to give the desired result. Many box colors do this is a single step but many color stylists may do them as separate processes.
Staining To Go Darker
Going darker involves adding color to your hair, essentially your hair gets stained by the color applied. Semi permanent colors sit on the outside of your hair shaft and wash out with a few shampoos.
Permanent colors on the other hand have molecules that are small enough to get inside the hair shaft. Once inside the hair shaft, there they react with each other to create polymers that would then be too big to get out of the shaft.
Unfortunately every time you get your hair wet, it swells with water especially if your hair has high porosity and as a result you will find that even permanent hair colors can get washed out and lose their vibrancy after a few shampoos.
For this reason, shampoos specifically made for colored hair are advisable to keep your color vibrant and reduce the number of times that you need to re-color your hair.