K18 Triple Bright Shampoo 125ml

A purple shampoo in a foam format, for blonde, silver and highlighted hair. K18 aims it at the cause rather than the symptom: the brass-inducing metals and minerals hard water leaves in the fibre. The brand states one wash removes up to three months of that brass.

What's in it

Sodium phytate and tetrasodium glutamate diacetate are the chelators, binding metals and minerals so they rinse away instead of sitting on the hair. The violet is Acid Violet 43 (CI 60730), formulated not to stain or overtone, and a biopolymer helps prevent minerals reattaching.

How to use it

Two to three pumps on wet hair, root to end. Leave one to three minutes — no longer — then rinse. Use up to once weekly in place of your regular shampoo: K18 designs it to detox and tone in one step. It rinses out with water and will not stain hands or clothes.

Who it's for

Highlighted and lifted tones, bleached or natural grey hair, and chemically bleached red. On extensions, keep to mid-lengths and ends, clear of the bonds. K18 has not tested it on natural red hair and does not recommend it there. Expect a squeaky-clean feel; K18 puts that down to mineral removal, not dryness, so follow with a conditioner or leave-in.