Black African Soap as a hair wash, how do you wash it out afterwards, or dont I?

[AndiFanni]

I have been using Black African Soap for my dry flaking scalp condition and it builds up as a white film deposited on my scalp which i can scratch off. Am i using it right? I thought i was rinsing it well but then maybe this is what happens? Can you help me. Also, if i bath in Shea Butter or Raw coconut oil should i rinse off afterward or just let it dry on my skin? Thanks