Common problems of water-resistant putty for interior walls

1. Common problems in putty powder:

1.1 Dries fast. This is mainly related to the addition of ash calcium and the water retention rate of the fiber, and also related to the dryness of the wall.

1.2 Peeling and rolling. This is related to the water retention rate, which is easy to occur when the viscosity of cellulose is low or the amount of addition is small.

1.3 De-powdering. This is related to the amount of ash calcium added, and it is also related to the amount and quality of cellulose added. It is reflected in the water retention rate of the product. The water retention rate is low and the hydration time of ash calcium is not enough.

1.4 Blistering. This is related to the dry humidity and flatness of the wall, and it is also related to the construction.

1.5 A pin point appears. This is related to cellulose, which has poor film-forming properties. At the same time, the impurities in cellulose react slightly with ash calcium. If the reaction is severe, the putty powder will appear in the state of bean curd residue. It can’t be put on the wall, and it doesn’t have cohesive force at the same time. In addition, this situation also occurs with products such as carboxyl groups added to the cellulose.

1.6 Volcanoes and pinholes appear. This is obviously related to the water surface tension of the hydroxypropyl methylcellulose aqueous solution. The water table tension of hydroxyethyl aqueous solution is not obvious. It would be fine to do a finishing treatment.

1.7 After the putty is dry, it is easy to crack and turn yellow. This is related to the addition of a large amount of gray calcium. If the amount of gray calcium is added too much, the hardness of the putty powder will increase after drying. Only the hardness and no flexibility will easily crack, especially when it is subjected to external force. It is also related to the high content of calcium oxide in gray calcium, which was introduced earlier.

2. Why does the putty powder become thinner after adding water?

Cellulose is used as a thickener and water-retaining agent in the putty. Due to the thixotropy of cellulose itself, the addition of cellulose in the putty powder also leads to thixotropy after adding water to the putty. This thixotropy is caused by the destruction of the loosely combined structure of the components in the putty powder. This structure arises at rest and breaks down under stress. That is to say, the viscosity decreases under stirring, and the viscosity recovers when standing still.

3. Why is the putty heavy in the scraping process?

In this case, the viscosity of the cellulose generally used is too high. Some manufacturers use 200,000 cellulose to make putty. The putty produced in this way has a high viscosity, so it feels heavy when scraping. The recommended amount of putty for interior walls is 3-5 kg, and the viscosity is 80,000-100,000.

4. Why does the putty and mortar made of cellulose with the same viscosity feel different in winter and summer?

Due to the thermal gelation of the product, the viscosity of the product will gradually decrease with the increase of temperature. When the temperature exceeds the gel temperature of the product, the product will be precipitated from the water and lose its viscosity. The room temperature in summer is generally above 30 degrees, which is much different from the temperature in winter, so the viscosity is lower. It is recommended to choose a product with a higher viscosity in summer, or increase the amount of cellulose, and choose a product with a higher gel temperature. Try to choose a product with a gel temperature above 70 degrees. Try not to use methyl cellulose in summer, its gel temperature is around 55 degrees, if the temperature is slightly higher, its viscosity will be greatly affected.