The open time of hydroxypropyl methylcellulose (HPMC) refers to the period of time during which the material can remain operable after application. During this time period, the material can be freely applied, shaped, and other operations without losing operability due to rapid drying. The opening time of HPMC is affected by various factors, including temperature, humidity, viscosity, etc. ‌

influence factor：

Temperature: Temperature is one of the main factors affecting the opening time of HPMC. Higher temperatures will accelerate the drying process of materials, thereby shortening the opening time. On the contrary, lower temperatures will prolong the opening time.

Humidity: Humidity can also affect the opening time of HPMC. Higher humidity will slow down the drying speed of materials, thereby extending the opening time; Lower humidity will accelerate drying and shorten the opening time.

Viscosity: The higher the viscosity of HPMC, the longer its opening time is usually. Because the high viscosity HPMC needs longer time to reach the gel state, which provides longer operation time.

Additives: Some additives may affect the opening time of HPMC. For example, certain thickeners or moisturizers may prolong the opening time, while certain desiccants may shorten the opening time.