Viscosity-increasing agents bentonite

Bentonites are extensively used in a water-based mud as a primary viscosifier (viscosity building agent]. Often, the consistency of yield of this mud is increased by adding polymers (Speers et al., 1988]. This practice allows poor yielding bentonites to be treated in order to meet the American Petroleum Institute (API] standards (American Petroleum Institute, 2008]. 

Finely divided solid particles that are wetted to some degree by both oil and water can also act as emulsifying agents. This results from the fact that they can form a particulate film around dispersed droplets, preventing coalescence. Powders that are wetted preferentially by water form O/W emulsions, whereas those more easily wetted by oil form W/O emulsions. The compounds most frequently used in pharmacy are colloidal clays, such as bentonite (aluminum silicate) and veegum (magnesium aluminum silicate). These compounds tend to be adsorbed at the interface and also increase the viscosity of the aqueous phase. They are frequently used in conjunction with a surfactant for external purposes, such as lotions or creams. 

Thickeners (viscosifiers and gelling agents] they are additives used to increase the drilling mud viscosities and gel strength at low concentrations. Among these additives are bentonite, xanthan gum, carboxymethyl cellulose, and guar gum. 

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