Wella Professional Welloxon Perfect 6% 20 Vol Crème Developer (1000ml) When used with Koleston Perfect this Welloxon crème developer offers the optimal consistency which makes for much easier and faster mixing as well as more precise application. This crème developer, with 6% 20 Vol allows for easy rinsing and a comfortable client experience; meaning less time is spent washing the hair. This Wella crème developer has been specifically reformulated to achieve the most accurate colour results. The consistency of this developer allows for excellent foil adhesion when foils are being used. This product has been specifically designed to use alongside the Koleston Perfect range to create a pure, high shine colour.