Viscosity is a measure of the flowability of a substance and describes its resistance to flow. Substances that flow more easily are referred to as low viscous and substances that flow more heavily and are thicker are referred to as higher viscous. For example, water is less viscous than honey, which in turn is less viscous than ketchup or toothpaste.

But what does viscosity look like under different stress conditions, e.g. when a substance is stirred? The following are some well-known examples from the food sector that everyone is probably familiar with. 

The examples in the videos show that the viscosity of a substance can also be strongly dependent on the stress applied. In some examples, the viscosity becomes lower with increasing stress (shear thinning). In other examples, the viscosity remains at a constant level, as in the case of honey, for example.