We recommend all colours, as well as Blonde.ID Bleach, to be mixed in a non-metallic bowl with a REF Cream Developer, using a non-metal whisk for smooth results. As with any colour, mix in a well-ventilated area. The processing time and mixing ratio will depend on product, hair colour, porosity and condition of the hair. It will also depend on the technique used, the volume of hydrogen peroxide and how many levels will be lifted.