Most people in the adhesives and sealants industry are aware of viscosity and realize that it characterizes the way a material will flow. More technically speaking, viscosity refers to a material’s resistance to flow; it can be measured in various ways, depending on the nature of the application. An evaluation of how the material is being processed in manufacturing or how the end user will try to apply it is the basis for determining the type of viscosity test that should be performed.
Imagine a caulk gun. The squeezing force required to expel the material out of the nozzle is important to know. If the caulk is not sufficiently viscous, too much will come out and some will be wasted. In addition, the caulk that does come out probably won’t hold its position on the substrate. Should the caulk be too viscous, it may not come out at all. In either case, the material is rejected and the customer is unhappy.