If the product vaporizes between the lapped seal faces it will separate the faces as the gases expand. When hot water vaporizes it leaves behind any chemicals that were dissolved in the water. Most of these chemicals are left in a hard crystal form that will damage the lapped faces. Fluids such as benzene and others with a low specific gravity, will freeze as they vaporize. If any oil or lubricant was placed on the seal face it will freeze and possibly damage the lapped faces.
Solvents vaporize with lower pressure leaving any solids behind.
Paint is a good example of a product where the solvent will vaporize at or below atmospheric pressure. In most cases you can reference a vapor pressure chart to learn when the solvent or carrier will vaporize in your application. Viscous Products - Their viscosity usually decreases with an increase in temperature and increases with a decrease in temperature. Oil is a good example of this type of fluid. High viscosity can interfere with free seal movement and cause seal face contact problems.