What are the differences between surface treated and non surface treated HPMC?

Non-surface treated HPMC

As we talked about before, the hot-dissolved type (Non-surface treated) is mainly applied in putty powder and mortar. By applying dry and even mixing, the HPMC in the resulting mixture will become separated by other materials. The viscosity will immediately build up after adding water and the resulting product will not clump together. 

In liquid glue and paint, there will be lumped. In contrast, it is available in a wide range of applications for instant type (Surface treated), in putty powder and mortar, as well as in liquid glues and coatings. There are no contraindications. However, for instant type (Surface treated), its water retention and stability are not comparable to hot soluble type (Non-surface treated). Therefore, we recommend hot soluble types in dry powder such as putty powder and mortar.

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.