The water temperature fluctuated greatly during dissolution, resulting in uneven dissolution of HPMC.
Insufficient stirring time or too short resting time, HPMC is not completely dissolved.
HPMC batch differences or improper storage conditions affect viscosity stability.
Solution:
Maintain a constant water temperature during the dissolution process, stir and leave it for enough time (usually 2-4 hours) waiting for HPMC to fully dissolve.
Stir again after dissolving to ensure uniform viscosity.
Regularly test the batch quality of HPMC to ensure consistency.
