When the correct testing and measurement methods are used, the result will surely be a consistent and good quality product. Conversely, if it is too thick, it would be hard to dispense it from the tube! Viscosity measurements can be used to help maintain quality and consistency in your products.Īt AMETEK Brookfield, we follow this simple rule: It is essential to ensure products have the look and feel that customers are expecting For example, if toothpaste is very runny, it would be challenging to use. Viscosity is a widely measured property and is critical, especially when it comes to quality testing in a wide range of industries. Like friction in moving solids, viscosity determines the energy required to make a fluid flow.

In other words, it can also be referred to as friction between the molecules in the fluid. Examples of such fluids are toothpaste, cosmetic creams, jam, mayonnaise, etc.Īt a molecular level, the interaction between molecules in a fluid causes viscosity. While water and honey, which are Newtonian fluids, behave this way, most fluids fluctuate depending on the shear rate -these other fluids are called non-Newtonian fluids. However, this is only true for some fluids. At a given temperature and shear stress, the viscosity of a Newtonian fluid would remain constant regardless of changes to the shear rate. This is where the Newtonian and Non Newtonian concept comes in. Water has low viscosity, whereas honey and oil both have higher viscosities.įluids may respond differently to changes in shear rate. Why does water flow faster than honey or oil? It is basically because of the difference in viscosities. In simple terms, viscosity can be referred to as the thickness of a fluid. Shear rate is the measure of the change in speed at which intermediate layers move with respect to one another. Shear stress is the force per unit area required to move one layer of fluid in relation to another. Viscosity is the measure of a substance's resistance to motion under an applied force – as per the definition.Ĭentipoise (cP), which is the equivalent of 1 mPa s (millipascal second). When there is relative motion between layers of fluid, viscosity can be defined and measured. Simply put, a fluid’s internal resistance to flow is called viscosity. Well, let’s begin by understanding what viscosity is and how it influences the quality of a product. Have you ever wondered why it takes more force to stir honey or oil than water or even milk? Why do some materials flow with greater ease than others? Or better still, why is this attribute even important in the world of testing and quality control?Ĭlearly, the attribute that we are talking about here is nothing but, Viscosity.

Is viscosity testing reliable