Hi , I m seeing a client on Thursday ( she is currently one of my nail clients ) , whos txted me about doing her hair aswell now . At a guess at the moment untill I see her then she has a level 10 color on her hair which she tells me she has colored herself ,( im not currently sure of her natural color yet ) .Shes asked for lowlights . I use Loreal and was wondering if anybody could advise if an 8.3 would work as she has a box dye on her hair ? I wanted to know if the previous dye forms a barrier before I go about doing a strand test ?