HOW TO GET THE BEST OUT OF THESE TONERS: Make sure that hair is level 9 or higher - see chart below to see what level 9 looks like. The hair should be at least yellow or lighter. Use with 7 Vol, 10 Vol or 20 Vol developer. Mix ratio is 1+1 Mix in an applicator bottle pour over hair, and rub in thoroughly. Make sure that all the hair comes into contact with the product. Leave in 10 minutes, and then rinse.