How do temperature and solvents affect viscosity?

temperature effect

Viscosity is greatly affected by temperature. Measurements should be performed at the same temperature (typically 23°C). A viscosity value without a temperature symbol is incomplete. Although each liquid is affected differently by temperature changes, the change in temperature per degree is usually a constant for a given material. The issue of temperature effects has been adequately discussed elsewhere. It can be said that the viscosity of the coating can be reduced by heating, and this principle is used in many coating application systems. Reducing viscosity by heating can also be used after the material has been applied. Preheating UV-cured coatings prior to UV exposure is often beneficial in leveling these sometimes sticky materials.

solvent effect

Higher resin solids yielded higher solution viscosity, while addition of solvent decreased viscosity. It is worth noting that viscosity changes are much more pronounced in the case of soluble resins (polymers) than in the case of insoluble pigments or plastic particles. For example, while a coating may be highly viscous at 50% solids, a plastisol suspension (plastic particles in a liquid plasticizer) may be moderately viscous at 80% solids. Different solvents produce different degrees of viscosity reduction, depending on whether they are true solvents, latent solvents, or non-solvents.