Understanding Bentonite Clay

Bentonite Clay is classed as a smectite – swelling clay that has powerful drawing and absorptive properties. There are four types of Bentonite Clay, also often referred to as Montmorillonite. They are - sodium, calcium, magnesium and potassium. They are identified and named according to the higher amount of one of the following exchangeable ions - sodium, calcium, magnesium and potassium. The most widely marketed are sodium and calcium. This is probably only due to availability.

Because Bentonite clay is such a versatile substance all types are used in a variety of industries that are unrelated to health and beauty. For example it is used in farming for sealing dams, oil drilling (as a lubricant) and for a base in road construction. The quality varies greatly and only the finer grades are suitable for health and beauty applications.

Does it matter which type of Bentonite I use? No it doesn’t matter which type as long as it’s of good quality because it’s all about the IONS!

What are IONS you might ask? IONS are atoms that have gained or lost one or more electrons. A common atom has no electrical charge but ions have a positive or negative charge. So ions are attracted to each other by their opposite charge. An exchange then takes place that is purely electrical. Thus it does not matter if the ions are sodium, calcium, magnesium or potassium because the electrical exchange does not discriminate.

For example Arsenic has a positive charge and is looking for a negative charge to balance its electrons. Because all types of Bentonite have negatively charged ions they will bond with arsenic. This is how clay can be used as an effective cleansing or detoxing agent if you like. It binds to positively charged heavy metals or toxins & locks them away. This is called adsorbing while absorbing is when clay swells and is stretched open like a highly porous sponge, drawing pollutants and toxins etc. into its internal structure, literally locking them away.

Furthermore, sodium Bentonite contains calcium as an exchangeable ion and calcium Bentonite contains sodium as an exchangeable ion. One factor that could make a difference is the conductivity of the substance. For example sodium is a better electrical conductor than calcium so there may be a minor advantage is this regard.

In any case all types of Bentonite are considered to be abundant with exchangeable negative ions and that’s positive for us!

What about the minerals in clay? The lists of minerals that make up the different types of Bentonite are very similar. However, given they are natural substances each varies in colour and texture and each deposit of clay has its own unique mix. For the purposes of using clay as a cleansing agent, knowing the mineral analysis might be interesting but it really is of no practical advantage as there is no way of utilising this information.

Conversely in agriculture knowing the mineral make up of clay deposits in a field helps the farmer prepare the soil for crops. Clayey soil is poor for growing things and the clay needs to be broken down or dissolved using a clay breaker such as gypsum or lime. This breaks the clay down into its individual minerals which then become part of the growing soil. It is important to know which minerals are present in the soil and which are deficient so as to produce healthy crops.

Can I absorb minerals from clay? There is growing interest in the idea that Bentonite clay may have some merit as a mineral supplement. It would be great if this was the case however laboratory tests for bioavailability confirm that the minerals are not in fact absorbable. This is due to the high bonding between the elements that make clay what it is.

This high degree of bonding is what prevents our digestive system from breaking it down in such a way that enables mineral uptake. The same of course applies to topical applications. Which makes sense because if we could in fact digest it would be dissolved into its individual elements and no longer be clay.

The benefits lay in clay remaining in tact. Consequently, if our digestive system is clean and functioning optimally then it follows that more efficient nutrient uptake is possible.

TASTE TEST: A simple taste test will verify for example that the sodium which is present in all types of Bentonite is not soluble in water. If you were to soak a teaspoon of any type Bentonite into a glass of water for 20 minutes and take a few sips you will not taste any saltiness. Bentonite is usually described as odourless and tasteless.

What matters? The first thing to know is that the clay you purchase is Bentonite clay because these are classed as smectites - swelling clay and have the ability to absorb toxins and pollutants at a high rate. A cation exchange of 50 -90 is ample and will be present in most Bentonite. It is important to choose volcanic clay and of course it must be pure / clean clay with nothing added. Some clay can have buffers and fillers. If taking it internally it must be stated on the label that it is food quality / edible.

The Bentonite clay we offer at Australian Healing Clay is a unique sodium Bentonite that is volcanic clay having a cation exchange of 90/meq. It occurs with high natural purity that meets food standards criteria as safe to ingest. It is BP grade – suitable for use with naturopathic and pharmaceutical medicines. Sun dried and dry milled into fine powder (45 microns). No other processing or treatment is done. It does not clump heavily like some Bentonite, making it easy to work with. When hydrated it has a soft velvety texture and produces a very smooth paste which is suitable for all applications.

French Montmorillonite clay which is actually sodium Bentonite has been commonly used by Europeans for many decades. French naturopaths have written about it and recommend it for all applications.


The screen mesh size refers to the milled or granular size of the finished product. It is a measurement of the fineness of the powder. Usually the finer the powder the quicker it will hydrate. However the milled or mesh size does not affect the performance of the clay. It is the fine particle size of Bentonite, meaning molecular size that provides a large surface area for absorption and is what separates it from other clay.

Australian 45 micron mesh size = USA 325 screen mesh. 

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