The addition of sodium carbonate found to influence the pH of common brick clays to varying extents. The effect varies depending upon the soluble salts presence in the clays. The higher the soluble salts the lesser will be the effect on improvement of plasticity by addition sodium carbonate.
In some clay mines its is usual […]

The lean plastic body like fire clay and fine fire clay in the moist condition is stored for several weeks or months to improve its plasticity before final shaping. In the real situation the non-plastic like grog materials are finely dispersed in the clay particles and the large surface area produced by this process enables […]

The oldest method of improve plasticity is aging or souring. This includes weathering and wintering. After mining the moist clay lumps is stored in the open yard so that it slowly disintegrates under the influence of moisture and temperature changes. The other effect of weathering in open atmosphere is the oxidation of impurities like pyrate […]

Based on the assumption of repulsive forces between the clay particles a formula was developed governing the relationship between shearing stress and impulsive forces. According to Forton the plasticity of a clay body is controlled by two forces;
1. The mutual repulsion of clay particles.
2. The surface tension of water which forces them together through the capillary action […]

The loose juxtaposition of clay particles is regarded as cause of thixotrophy by which we mean the spontaneous liquefaction of a semi stiff clay body on shaking and its re-consolidation on restoring the condition of rest. It is more in plastic bodies where alkalies have been used in their preparation. Water bound by the sodium […]

The capillary suctional forces are directly proportional to the surface tension of the liquid. A clay slip exhibits the effect of surface tension the more manifestly the more time it is given to develop them. The surface tension of water and its boundary surface tension against clay and plaster are the primary causes of cohesion […]

Algae spread through the whole mass and behave like a gel, which facilitates deformation. The effect is equivalent to other organic and inorganic colloids, which by their swelling behaviour increase their plasticity. However the effect is lesser than that of humic acid which is able to break down clay aggregates into individual lamellae.
To sum up, […]

The role of water films in plasticity is very important, however in addition organic matter both animate and inanimate contributes to plasticity. Bacterias found in water and soil live in clays especially in clay bodies, though they appear to be present only on the surface of freshly mined clay. Clay that has been sterilized […]

Even non-plastics such as quartz or zirconium di oxide can be converted into fictile masses through prolonged fine grinding. But they have no cohesion and flow like casting slip. There is a connection between the lamellar shape and plasticity. And hence it is considered that the lamellar form of clay particles to be the most […]

Beside refractoriness the most important industrial property of clay is its plasticity. This is nothing but the capacity of forming a fictile dough with water which holds firmly together during shaping and retain its shape during drying and firing. All this property depend on the traditional methods of shaping the clay on hand or by […]