What term is used to describe the thickness of a solution?

Viscosity refers to the thickness or internal resistance of a liquid to flow. It indicates how quickly a liquid can pour or spread, with higher viscosity liquids being thicker and more resistant to flow. For instance, honey has a higher viscosity than water, meaning it is thicker and flows more slowly. Understanding viscosity is particularly important in haircoloring, as it can impact how easily a dye can be applied and how evenly it spreads on the hair.

Density, on the other hand, describes how much mass is contained in a given volume of a substance, not its thickness or behavior in terms of flow. Consistency often relates to the texture or quality of a substance but does not strictly refer to the technical concept of thickness in liquids. Fluidity is a term that explains the ability of a substance to flow, which can be somewhat interchangeably discussed with viscosity but does not define its thickness directly. Therefore, viscosity is the most precise term to describe the thickness of a solution.