When bleaching your hair, your locks go through several levels of lightening, the lightest being pale yellow. Very rarely can you get a white-blond result without using some sort of special toner that contains purple hues. Purple neutralizes yellow tones in your hair, keeping your bleached or silver tresses bright. There are toning purple shampoos available for purchase, but you can make your own purple shampoo with food coloring.
Start with a full bottle of moisturizing shampoo. It is best if the shampoo contains no dyes so it is easier to see how purple you are making it.
Add two or three drops of purple food coloring if you are using 12 to 18 oz. of shampoo. For smaller bottles, add one drop at a time until you achieve the right level of color.
Close the shampoo bottle and shake it vigorously to mix the purple food coloring well. Take a look at the shampoo. It should only be lightly tinted with purple. If you cannot see any purple hue, add one drop at a time until the color is visible.
Shampoo your hair immediately after bleaching. Making homemade purple shampoo is a trial-and-error process; you may have to add more drops to get the results you desire. Make any adjustments needed until the shampoo deposits enough purple onto your hair to neutralize the yellow tones.
Use the purple shampoo every day in between salon visits. If you start noticing a purplish cast to your hair, use the shampoo every other day, or only once a week.