Plasticity:

Plastic behavior is characterized by the presence of a yield value. Some materials like semisolids do not flow at low shear stress. A Bingham body dose not flow until shearing stress equals or exceeds the yield value. When the shear stress equals or exceeds the yield value, the composition begins to flow. This system exhibits solid like behavior under quiescent conditions. Agitation temporarily disrupts the rigid network of solids making it possible to poor or apply the suspensions to the skin.