I am a professional hair stylist and I often add concentrates to my existing (Wella Keleston and ColorTouch) colors to encourage or discourage different tones in order to "personalize" each application. One situation comes to mind: two of my clients are twins of Egyptian descent. Their hair is quite dark, but because they are sensitive to having "identical" hair color, I differentiate by mixing a gold concentrate into one of their formulas and a little red/violet in the other. Is it possible with EcoColors to add golder tones to the darker shades? Also, I like to add a little blue/green concentrate to color mixtures of level 8 or 9 to highlight dark hair to get that sort of "paper sack" (for lack of a better term) color without the red. How is that done? Barry