Clay Science: Bentonite and Rhassoul
Rhassoul much like bentonite clay is pretty much what it says on the bottle - mud! These two clays actually do not have much hair or skin related research about them despite being extensively used in spas as mud baths and wraps. Rhassoul (also Ghassoul) originates from Morrocco while bentonite is much more widespread.
How do they work?
The primary use of these clays is for cleaning.The clays are able to attract small dirt particles to themselves and hold onto them. This is known as adsorbing (with a D). The clays typically attract positively charged ions (cations). The clay and the ions that it has held onto can then be washed off. They also remove heavy metal toxins such as lead (Journal of Hazardous Materials, pp243-249, 2005).
Does Rhassoul or Bentonite Clay damage hair?
Sorry, don't know! The clays tend to be very fine and they can actually be used in cosmetics to thicken up formulations . This is because they are non irritating to skin and do not cause it to break out - non comedogenic (JSCC, pp 321-333,1989). As the particles are very fine, they are not really known to damage the surface of skin or hair but there is no concrete proof that they don't.
Does Rhassoul or Bentonite Clay increase curl definition?
I have seen many blogs and youtube videos with many people reporting this. I think that if your hair type is the kind that spirals up then it is possible that it will. However, if your hair is like mine and simply does not do curl definition then it just won't work.
Do you need to follow up with a conditioner?
Some say nay, some say. If you are curious, there is only one way to find out though - buy some, try some.