Purple shampoo works by neutralising unwanted yellow or brassy tones that can develop in blonde or lighter hair colours overtime. The reason for this lies in colour-theory science. Colours that are opposite each other on the colour wheel cancel each other out when combined. In the case of hair, yellow and purple are opposite each other on the colour wheel, therefore when purple pigments are applied to yellow/brassy tones, they help neutralize the unwanted colour, resulting in a cooler shade. Purple shampoo contains violet or purple pigments that are deposited onto the hair during the shampooing process. These pigments counteract the warm tones by toning them down. When you apply purple shampoo to your hair and leave it on for a few minutes, the purple pigments penetrate the hair shaft and adhere to the brassy or yellow areas, effectively cancelling out those colours. By removing these yellow-orange tones, blonde hair looks richer and lighter and creates a more consistent, quality hair colour.

Start by washing your hair in warm water to open the cuticles, apply the purple shampoo and massage from roots to tips. Leave the purple shampoo in your hair for one to two minutes before rinsing out. Follow-up with a purple conditioner to help seal the cuticle, keeping your hair feeling softer and healthier

Depending on your hair colour, it’s often best to start using purple shampoo once a week, as overuse can result in a darker or duller tones than intended.

Contrary to the online-sparked belief that toner shampoos work better on dry hair, which is believed due to dry hair being more porous, toner shampoos should only be used on wet hair. Applying purple shampoo to dry hair can result in uneven application and cause a patchy finish. Wet hair provides a consistent surface for absorption, which allows for more even coverage and a better finish.