Looking for an advice
Which of the wella is better to cover to cover light blonde hair in order to achieve a natural dark brown hair,KP 4/0 with 6% 1:1or CT 4/0 with 4%??
For a long lasting and good coverage result!!
I’d probably use CT rather than a permanent colour as this will last better. Also use a red with some brown mixed in to pre-pig as the undertone of a level 4 is red/brown.
However, are you sure the client wants to go as dark as a 4 from being light blonde?
What sort of skin tone do they have? Do they want a warm rich chocolate colour or a flatter cool colour?
A straight 4/0 could look very matte and for instance, make a sallow skinned person look quite ill.
If the client has been blonde for a while, they can panic when going darker so I tend to take them darker over a couple of sessions with lowlights to get used to their new look. You don’t want to spend ages doing a beautiful rich deep colour to have them (or their annoying partner!) complain and insist on going back to blonde the next day.