What does viscosity refer to?

Viscosity refers to the relative thickness of a liquid substance, which indicates how resistant the liquid is to flow. In the context of lash extensions, understanding viscosity is particularly important because it can affect how well a product, like adhesive, spreads and interacts with the natural lashes. High viscosity materials are thicker and flow less easily, whereas low viscosity materials are thinner and flow more freely. This property influences the performance of the products used, including drying time and application techniques, making it a crucial concept for a lash technician. The other options, while related to different physical properties, do not accurately describe viscosity.