How can a clay be selective ?

Clay is at the origin of life. It served as a model to elaborate the first organic molecules (cf. the Genesis in the Bible).
Therefore it is not surprising that clay has the capacity to give what is favourable to life (its trace minerals) and to retain what is unfavourable to life (toxins or rotten matter).

How can a clay retain what is contrary to life ?

Because of its planar molecular structure, clay has the capacity to ad-sorb elements contrary to life, retaining them without letting them go.

For this reason, it is always advised to use only once, and to throw after use (impossible to wash it for later re-use).


How can good clay be distinguished from clay with low activity ?

There exists a very precise technology which measures the quantity of trace minerals that clay can exchange for 100g. The measurement unit is the quantity of « milliequivalents per 100g » or « meq/100g ». It is a point of utmost importance when deciding to buy clay for medical purposes. In fact it is very easy to encounter all sorts of clays supposedly medicinal, but in reality they are only ordinary clay without much therapeutic value (which some unscrupulous manufacturers try and sell on a more lucrative market).
The only effect of such clay is that of a sponge, much in the same way as a piece of cotton.
If this measure in meq/100g is not indicated on the pack, most likely the clay is a common one, or pottery clay…
Ordinary clay is a very common material, therefore it is very economical, whereas a medical clay is is much more expensive due to its rarity.
It is important to be very careful when clay is economical.
For clay to be really active therapeutically, the ionic exchange value must be at least 70meq/100g.

Is it possible to recognize the properties of a clay depending on its color ?

Unfortunately the color of a clay depends solely on the pigments it contains ( mostly ferrous oxydes) and not on the structural qualities responsible for its therapeutic actions.
There exists for instance yellow, pink and green Montmorillonites clays… but they are always Montmorillonites with all their intrinsic qualities.