I wanted to create a purple shampoo that is great for toning blondes + brunettes and is also sulfate-free... I’ve always had a hard time finding that combo. If you like ashy tones or even pastel lavender tones, you can use this every time you shampoo. If you like neutral tones, use it only when needed to cut brass. Use this with or without The One Purple Conditioner on natural or color-treated hair.