On the Knotty Boy website they recommend the Knotty Boy Residue Free Natural Dreadlock Shampoo. This shampoo is the world's first dreadlock-specific shampoo. This shampoo is made from saponified vegetable and organic essential oils, so that it does not undo the locking process or leave any residue.
Knotty Boy sells both liquid shampoo and a shampoo bar. An alternative to Knotty Boy is found on the website of Dreadlock Shampoo. This is an all-organic dreadlock shampoo site that sells both shampoo bars and liquid shampoo as well. These shampoos are good for the scalp and do not include any harmful chemicals, as well as being environmentally friendly.