The role of Hydroxypropyl Methylcellulose in mortar and putty powder-HPMC

Industrial-grade HPMC powder is a key product of Shijiazhuang Cellulose Co., Ltd. This product serves as a thickener and water-retaining agent for cement used in construction, ensuring excellent workability. HPMC powder is widely used and appreciated globally.

Hydroxypropyl methylcellulose (HPMC) is a key additive in mortar and putty powder.

 I. Core Functions

Strong Water Retention:HPMC locks in moisture, prolonging the hydration time of cement/plaster, preventing cracking, powdering, or insufficient strength caused by rapid moisture evaporation, and ensuring full hardening of the material.

Mechanism:Hydrophilic groups in the molecule form a "moisture-protective film," slowing down moisture loss to the substrate and air.

Thickening and Improved Workability:Increases the viscosity of the slurry, reducing sagging during vertical surface application; imparts "thixotropic" properties to the material: high consistency when standing (prevents sedimentation), decreases viscosity during application (easy to spread), and quickly recovers consistency after application (maintains shape and prevents collapse). Makes application smoother, reduces splashing, and improves construction efficiency.

Enhanced Adhesion and Crack Resistance:Improves the adhesion between putty/mortar and the substrate, reducing hollow areas and peeling; fills gaps between particles after hardening, reducing shrinkage and minimizing microcracks; alleviates expansion cracking caused by rapid hydration in gypsum-based materials.

II. Application Differences Among Different Materials

Cement-based Putty/Mortar

Function: Optimizes pumpability, extends workability, and reduces sagging (e.g., plastering mortar, tile adhesive).

Dosage: 0.1%-0.3% (mortar), 0.2%-0.4% (putty powder).

Gypsum-based Materials (Plastering Gypsum, Self-leveling Mortar)

Function: Improves uniformity, extends setting time, and increases surface smoothness.

Tile Adhesive

Function: Increases open time (workability window), improves sagging resistance and bond strength.

III. Usage Precautions

Type Selection:

Cold Water Instant Dissolver:Suitable for liquid adhesives, coatings, and dry powders requiring rapid dissolution.

Hot Melt Type: For dry powder mortar/putty only; mix directly.

Dissolving Method:When mixing dry powder, stir thoroughly with other powders before adding water to prevent clumping.

Environmental Compatibility: Increase dosage in high-temperature, dry environments (higher water retention requirements).

High Viscosity Type (e.g., 150,000-200,000 mPa·s):Suitable for anti-sagging applications.

In summary, HPMC, with its three core functions of water retention, thickening, and enhanced adhesion, has become an indispensable additive for mortars and putty powders. Its specific application requires adjustment of type and dosage based on material type (cement/gypsum-based), construction environment, and performance requirements to achieve optimal construction results and finished product quality.