Wella koleston perfect mixing question? I purchased the following hair colors 66/0, 77/0 and 7/01 ash since I have 75 to 100% gray I am using 20 volume with a 1:1 ratio. I was going to mix 1oz of the 66/0 and the same for the 77/0. Should I mix the same amount of the 7/01 or just 1/2 oz. Please help.