differences between construction grade hpmc and personcal care grade hpmc

Surface treated HPMC

Compared to the non-surface treated HPMC, the instant type (Surface treated) HPMC has a wider application area. It can be used in ash calcium-based putty and cement-based mortar, as well as in glues and coatings. Under an alkaline condition, the instant type HPMC can achieve a certain calibrated viscosity. In a gypsum-based mortar, due to the acidic pH value of gypsum, the delayed solubility of hydroxypropyl methyl cellulose (HPMC) will only become viscous very slowly. 

The initial setting of construction-grade gypsum can be achieved in or more than 3 minutes. Yet, the final set can only be formed in or less than 30 minutes. Although a certain amount of retarder is required in the gypsum-based mortar to delay the time of setting, the operating time of the resulting gypsum-based mortar is still not as good as the cement-based and gypsum-based products. So, some alkaline materials must be added to increase the time of the HPMC becoming viscous.