The One Purple ShampooI love brass… in my house, not your hair. I wanted to create a purple shampoo that was both great for toning and also sulfate-free because I've always had a hard time finding that combo. If you like ashier tones, you can use this every time you shampoo. If you want more neutral tones, use it every other time you shampoo to balance out unwanted brassiness. It can be used with or without The One Purple Conditioner. And yes, this shampoo can be used on color treated or naturally blonde hair.One and done.Toning time!How to:1. Depending on the thickness of your hair, apply a dime to quarter-sized amount of shampoo into your palm.2. Apply to wet hair, massaging into the scalp to create a rich lather.3. With purple shampoo you want to make sure you apply more product where you see more brass. I like to let it sit a little longer toward the top where hair is less porous and tends to be warmer in tone (2-3 min), then I let it run down through the ends where it's more porous for less time (1-2 min). 4. Rinse well and follow with conditioner.Tip: If ever you go overboard and your hair gets too ashy for your liking, just shampoo once with The One Signature Shampoo to remove one level of tone.PATCH TEST: Apply a small amount of product to dry, cleansed inner side of elbow. Wait for 48 hours. Do not use this product if you experience any burning, redness, swelling or itching.