I found that with bentonite, rhassoul, and pink clay I would get a lot of build up, especially if I added oils to my mixture. I personally, don't mind a little bit because I have found over the years that if my scalp is squeaky clean from shampoos that my scalp and hair gets dry, flaky, and brittle. I've since switched to kaolin clay which I've found much easier to wash out. It has more of a lotion consistency or like milk if you make it too thin. It also doesn't dry your hair out as quickly as some of the other clays do. I always follow up with conditioner just to be on the safe side. I've learned the hard way that without doing that step I could end up walking around with "sand" in my hair until the next wash day.