3. Hydroxypropyl Methylcellulose has stability to acids and bases and its aqueous solution is very stable at pH 2-12. Caustic soda and lime water have little impact on its performance. but bases can accelerate its dissolution rate and slightly increase the viscosity. Hydroxypropyl Methylcellulose has the stability to general salts, but the Hydroxypropyl Methylcellulose solution viscosity will tend to increase when the concentration of the salt solution is high.