Bentonite clay (or montmorillonite clay) is a highly absorbent all-purpose powder that binds with dirt, toxins, and product residue on skin and hair. It is non-toxic therefore under certain conditions it is also taken internally. The main use for hair is as a gentle, heavy-duty cleanser. It works equally well for natural hair, for locs and for chemically and colour processed hair. The caveat with coloured or dyed hair is that you should not apply the clay soon after colour processing otherwise you might strip the colour.
Once you purchase the bentonite clay powder there are several recipes online that you could use to mix and apply it. The simplest is to mix a few tablespoons of the clay depending on the length of your hair, with apple cider vinegar, water or aloe vera juice, and an oil of your choice. Combine well and apply directly onto dampened hair. Leave it on for 5 minutes if you are in a hurry or up to an hour. If you have traditional locs, leave it for several minutes to allow the clay to draw out lint and impurities that have been embedded deep into your locs. Rinse out and style as normal. There is usually no need to deep condition after doing this treatment.