1 Introduction
HPMC (Hydroxypropyl Methyl Cellulose) is a nonionic cellulose ether widely used in building materials, including gypsum plaster. As an important functional additive, HPMC improves the processing properties and application characteristics of gypsum plasters.

2. Main properties of HPMC
HPMC is a polymer compound obtained by chemical modification of natural cellulose. Its features include:

Water solubility: HPMC can dissolve quickly in cold water, forming a clear or slightly milky solution.
Thickening: Can significantly increase the viscosity of the solution.
Gelling: HPMC has unique thermal gelling properties, and the solution regains fluidity after cooling.
Water retention: In building materials, it can effectively improve the water retention of materials and extend the operating time.
Lubricity: Improve the lubrication properties of the material to facilitate construction and application.

3. The role of HPMC in gypsum plaster
3.1 Improve water retention
HPMC increases the water-holding capacity of gypsum plaster and reduces the rapid evaporation of water. This is very important for the construction and shaping of gypsum plaster, as sufficient water retention ensures uniform drying of the plaster and avoids shrinkage and cracks.

3.2 Enhance adhesion
HPMC improves the bond between stucco and substrate. This helps improve the bond strength of the plaster and prevents peeling and hollowing, thereby extending its service life.

3.3 Improve construction performance
HPMC increases the viscosity of gypsum plaster, making it easier to apply and create a smooth surface. In addition, HPMC enhances the lubricity of the stucco, making it easier for construction tools to operate, thereby improving construction efficiency and quality.

3.4 Prevent sagging
HPMC improves the consistency and rheology of the plaster, preventing the plaster from sagging and sagging during construction, thus ensuring the smoothness of the wall.

3.5 Increase opening hours
HPMC increases the open time of stucco, giving construction crews more time to trim and work on, avoiding construction defects caused by lack of time.

4. Dosage and usage of HPMC
4.1 Dosage control
In gypsum plaster, HPMC is usually added at levels between 0.1% and 0.5%. This depends on the specific formulation of the stucco, application requirements, and environmental conditions. Dosage that is too high or too low may affect the performance of the stucco, so adjustments will need to be made based on actual conditions.

4.2 How to use
HPMC should be evenly dispersed in the dry powder and then mixed with the other ingredients. Usually during the preparation process of stucco, HPMC is added to the uniformly stirred gypsum powder, then an appropriate amount of water is added, and the mixture is mixed until a uniform consistency.

5. Advantages of HPMC in gypsum plaster
5.1 Environmental protection
HPMC is a non-toxic, non-polluting green chemical. Its application will not have adverse effects on the environment, which is in line with the environmental protection requirements of modern building materials.

5.2 Economy
Due to the high efficiency of HPMC, its addition amount can significantly improve the performance of gypsum plaster, so it has a high cost performance.

5.3 Stability
The performance of HPMC in gypsum plaster is stable and will not fluctuate significantly due to changes in temperature and humidity. It is suitable for various construction environments.

6. Practical application cases
In actual construction, gypsum plaster added with HPMC has been widely used in wall plastering, ceiling painting, building repair and other fields. For example, when painting interior walls of buildings, adding HPMC to gypsum plaster can effectively prevent cracks and powder loss problems and provide better wall finishing effects.

The application of HPMC in gypsum plaster not only improves the physical properties of the material, but also improves construction quality and efficiency. Its superior water retention, adhesion and construction properties make it an indispensable component of modern building materials. In the future, as the construction industry’s demand for high-performance, environmentally friendly materials increases, the application prospects of HPMC will be even broader.