ALWAYS do a strand test and an allergy test according to the kit directions before applying any new color to your entire head. This way you can see how your hair will look on a small section . If you do not like the end result, you can be happy you did not apply it to your entire head. If you LOVE it, the proceed with the color instructions and apply the color to your entire head.Apply equal parts color to developer. Apply to roots only if you have previously colored ends. The last 5-10 minutes of processing time you dilute the remaining color developer mixture by half with water to apply to the previously colored ends. If your ends are porous, you always apply in a diluted formula to the ends. If your ends are previously colored you always apply a diluted formula on the ends. These instructions come in the kit. For resistant gray leave the color mixture on the grays for 45 minutes with plastic cap. EcoColors hair color is PPD FREE.