Grey hair in hair systems and wigs can be tricky. There is a “white” grey and a “silver” grey. If one needs a white grey, it is best to have a little synthetic (sometimes all synthetic) to keep the brightness in the color. An all human hair unit will tend to get ashy due to oxidation. It is recommended to use a bluing shampoo (it looks purple in color though!) to help retain the crispness to the white. Too much bluing, however, can stain the hair a blue tone so it is best to dilute the shampoo at first to avoid any staining. As always though, best practices would be to consult with your hair correction professional before making your decision.