Common Problems and Solutions for Using Interior Wall Putty Powder
Release Time:
2020-07-10
Source:
Common Problems and Solutions for Using Interior Wall Putty Powder
1. Common problems with putty powder:
1.1 Fast drying. This is primarily related to the increased dosage of hydrated lime powder (if the dosage is too high, the amount of hydrated lime in the putty formulation can be appropriately reduced) and the water-retention capacity of the fibers, as well as the dryness of the wall substrate.
1.2 Peeling and curling. This is related to water retention; low cellulose viscosity can easily lead to this issue, or it may occur when the dosage is too low.
1.3 Powder shedding from interior wall putty. This is related to the amount of hydrated lime powder added (if the dosage of hydrated lime in the putty formulation is too low or its purity is insufficient, the dosage should be appropriately increased) as well as to the amount and quality of cellulose, which is reflected in the product’s water-retention rate; a low water-retention rate indicates that the hydrated lime This is caused by insufficient hydration time, resulting in incomplete conversion of calcium oxide in the lime powder to calcium hydroxide.
1.4 Bubbling. This is related to the moisture content and flatness of the wall, as well as to the construction process.
1.5 Pinholes appear. This is related to the cellulose: its film-forming properties are poor, and at the same time, impurities in the cellulose react slightly with lime. If the reaction is vigorous, the putty powder will take on a crumbly, tofu-like consistency, rendering it unsuitable for application to walls and completely lacking adhesion. Additionally, this phenomenon can also occur when carboxymethyl derivatives are added to the cellulose. This kind of situation.
1.6 Volcanic pores and pinholes appear. This is clearly related to the surface tension of hydroxypropyl methylcellulose aqueous solutions; the surface tension of hydroxyethyl solutions, by contrast, is not as pronounced. Performing a light-reflecting treatment will improve the situation.
1.7 Putty is prone to cracking and yellowing after drying. This is closely related to the excessive addition of hydrated lime powder; when too much is used, the putty hardens significantly upon drying, but hardness without flexibility makes it easily crack—especially under external stress. It is also linked to the high calcium oxide content in the hydrated lime powder, as mentioned earlier. Shao's.
2 Why does putty powder become thinner and thinner the more you stir it after adding water?
Cellulose is used as a thickening and water-retaining agent in putty. Due to cellulose’s inherent thixotropy, the addition of cellulose to putty powder also imparts thixotropic behavior to the putty upon hydration. This thixotropy arises from the disruption of the loosely bonded structural arrangement of the putty powder’s constituents. When at rest, this structure... It breaks down under stress, meaning its viscosity decreases during stirring and recovers when at rest.
3. Why is the putty relatively heavy during the application process?
This situation typically occurs when the cellulose viscosity is too high. Some manufacturers use a product with a viscosity of 200,000 for putty, which results in a putty that feels heavy and sluggish during application due to its excessive viscosity. For interior wall putty, the recommended addition level is 3–5 kilograms, with a viscosity of 80,000–100,000.
4. Why does putty and mortar made with cellulose of the same viscosity feel differently viscous in winter versus summer?
Due to the thermogelling property of the product, its viscosity gradually decreases as temperature rises. When the temperature exceeds the product’s gelation temperature, it will precipitate out of the water, thereby losing its viscosity. In summer, room temperatures typically exceed 30°C, which is a significant difference from winter temperatures; therefore, the perceived viscosity We need a lower viscosity. During summer, it is recommended to choose a product one viscosity grade higher whenever applying the formulation, or to increase the cellulose dosage. Alternatively, select a product with a higher gelation temperature; preferably opt for an MK-grade product, as this type typically has a gelation temperature of 70°C or above. In summer, avoid using methyl-based products whenever possible. Cellulose has a gelation temperature of about 55°C; even a slight increase in temperature can significantly affect its viscosity.
