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 neutralises 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 colouring.
Start with a full bottle of moisturising 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 colouring if you are using 354 to 532ml. of shampoo. For smaller bottles, add one drop at a time until you achieve the right level of colour.
Close the shampoo bottle and shake it vigorously to mix the purple food colouring 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 colour 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 neutralise 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.
Don't leave the shampoo on your hair for too long when showering. The longer you leave the shampoo in your hair, the more colour will deposit onto your locks.