Solubility of HPMC in Hot Water

HPMC is not readily soluble in hot water; therefore, it is necessary to cool the HPMC hot solution to an appropriate temperature. Only under these conditions can HPMC dissolve and effectively enhance viscosity. There are three recommended approaches:

a. Pour the necessary amount of hot water into the container and heat it to approximately 70°C. Slowly stir the heated water and add HPMC to it. Initially, the HPMC powder may float on the water surface, gradually forming a slurry through continuous stirring. Continue stirring until the slurry cools to an appropriate temperature, at which point HPMC becomes water-soluble, and the solution gains viscosity.

b. Pour either 1/3 or 2/3 of the required hot water amount into the container and heat it to around 70°C. Add HPMC to the heated water, stirring slowly to ensure even dispersion and thorough wetting of the HPMC powder. Create a hot water slurry. Then, add the remaining amount of cold water to the hot slurry, cooling the mixture while maintaining continuous stirring.

c. Place either 1/3 or 2/3 of the needed hot water into the container and heat it to approximately 70°C. Slowly stir the heated water to disperse and wet the HPMC powder thoroughly. Create a hot water slurry. Add the remaining amount of cold water or ice water to the container. Introduce the HPMC hot water slurry to the cold water and stir continuously. Finally, allow the solution to cool down.