Hello.
I have a client who is 100% white and insists on only Schwarzkopf colour, however I use Wella (long story how I got her as a client!)
She is a base 8, when she came to me she had a card saying 8/0 and 8/45 and 20vol. She hates any warm. Anyway, I had 8/0 and 8/4 in salon by chance so...