What does "double processing" refer to in hair coloring?

"Double processing" in hair coloring specifically refers to the technique of applying bleach followed by a toner to achieve the desired shade. This method is commonly used to lighten hair significantly and then refine the color to meet the client's preferences or to neutralize unwanted tones.

The first step, bleaching, removes the natural pigments from the hair, lifting the color to a lighter shade. However, this process can sometimes leave the hair with a brassy or overly yellow hue. The second step involves applying a toner, which deposits color onto the hair to create the desired finish, whether that’s a cool blonde, ash, or another nuanced shade. This two-step process is essential for achieving a polished and professional look, especially in color corrections or dramatic hair changes.

The other options do not accurately reflect "double processing" as recognized in professional hair coloring practices. Shampooing hair twice before coloring can be part of a preparation routine but is not related to the double processing technique. Using two different brands of hair dye may be a choice some stylists make for specific tones but does not define double processing. Finally, coloring hair in two separate appointments could indicate a sequential approach to hair coloring but lacks the core aspect of intensive processing involved in the bleach and toner method.