When we use putty powder, there will often be some problems, so we don’t know the reason. I think there should be seven kinds of problems that often appear in putty powder!
One: Do it 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.
Two: peel and roll. 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.
Three: powder removal. 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.
Four: Blistering. This is related to the dry humidity and flatness of the wall, and it is also related to the construction.
Five: 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.
Six: Volcanic caves and small holes appear. This is obviously related to the water surface tension of hydroxypropyl methylcellulose aqueous solution, but the water surface tension of hydroxyethyl aqueous solution is not obvious. It will be better to carry out light treatment.
Seven: 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.
1. Why does the putty powder become thinner after adding water?
Cellulose ether 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.
2. What is the reason why the putty is relatively heavy in the scraping process?
In this case, the viscosity of 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.
3. 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 when applying the product in summer, or increase the amount of cellulose, and choose a product with a higher gel temperature
Post time: May-22-2023