What happens to the viscosity of a primer when the solvent content is decreased?

When the solvent content of a primer is decreased, the viscosity typically increases, leading to the primer becoming thicker. This occurs because the solvent acts as a thinning agent, reducing the overall viscosity of the mixture. As the solvent evaporates or is removed, the concentration of solids in the primer increases, resulting in a thicker consistency.

In the context of application, a thicker primer may impact how it adheres to surfaces and how it is spread during installation. It is important for users to understand this relationship when preparing primers for use in built-up roofing systems, as the viscosity can affect both application methods and the final performance of the roofing assembly.