HPMC (Hydroxypropyl Methyl Cellulose) is commonly used as an additive in wall putty, stucco and surface coating formulations. It is a multifunctional polymer derived from cellulose that offers several advantages in these applications. Here’s how HPMC is used in wall putty, stucco and skim coats:
Water retention: HPMC increases the water retention of the mixture, allowing the material to remain usable for longer. This is especially useful in construction applications where extended operating hours are required.
Workability: HPMC enhances the workability of the mixture, making it easier to apply and spread evenly on surfaces. It helps achieve a smooth and even finish.
Adhesion: HPMC improves the adhesion of wall putty, stucco or surface coating to the substrate, ensuring a better bond and reducing the likelihood of cracking or peeling.
Sag Resistance: HPMC helps reduce sag or collapse of the material in vertical or overhead applications. It imparts thixotropic properties, allowing the mixture to hold its shape and stay in place.
Crack resistance: By adding HPMC, the final coating exhibits improved crack resistance due to its increased flexibility. This helps prevent cracks caused by substrate shrinkage or movement.
Film Formation: HPMC forms a film when dry, which helps improve the durability and water resistance of wall putty, stucco or surface coatings. It protects the underlying surface from moisture penetration and prolongs its life.
Rheology Control: HPMC acts as a rheology modifier, affecting the flow and consistency of the mixture. It enables easy application by controlling viscosity and preventing settling or separation of solid particles.
It is important to note that the exact amount of HPMC and other formulation ingredients may vary depending on desired properties, application method and environmental conditions. Manufacturers of wall putty, plaster and skim coating products often provide guidance on the proper use of HPMC in their technical data sheets or product descriptions.