Dual process hair coloring involves removing the original hair color.
Taking a person’s natural hair color and then applying a new color is called dual process hair dye. It is usually done by changing from a dark hair color such as brunette to a much lighter blonde color. This two-step color changing process is permanent and the natural color will be noticeable as the hair roots grow back.
In a dual hair color change process, the first step is known as bleaching. Ammonia and peroxide are used to strip most of the hair’s natural color. It is important to keep the bleach solution away from the scalp to avoid skin irritation. At this point, the hair will likely look yellow or orange.
Toning occurs when the new color is added during the second step. The new hair color mixes with the small amount of natural color molecules that remain in the hair. The resulting combination is the new permanent color that cannot be removed.
A radical change in hair color may require a two-fold process.
Because the new color reacts with a person’s natural hair, the same hair dye can look different on each person. A yarn test is recommended to visualize the color. In this test, only a small section of hair is dyed so that the person can see what the new hair color will look like before dyeing all the hair.
Care must be taken to preserve and protect double-dyed hair. Special shampoos and conditioners are available to keep hair color shiny and protect it from breakage. As the color change is dramatic, double-processed hair will need frequent touch-ups as the hair grows out to reveal the natural color at the root. The same process can be used to color the roots to ensure they match the rest of the hair.
There are several shampoos and conditioners formulated for use on colored hair.
These dramatic color changes can cause severe hair damage. A more subtle process called single process dyeing can limit breakage. In a single process, a new color is added to the natural hair color in one step. The natural color is not removed and instead the two colors combine to create a new hair color.
Adding color highlights is another option. Ammonia and peroxide are used on certain parts of the hair to lighten the hair, causing a change that is usually less dramatic. Highlights create a mix of natural and dyed hair colors and are often worn around the face to brighten the skin tone and eye color.