1 Common problems in wall putty powder:
(1) Dries fast.
This is mainly because the amount of ash calcium powder added (too large, the amount of ash calcium powder used in the putty formula can be appropriately reduced) is related to the water retention rate of the fiber, and it is also related to the dryness of the wall.
(2) 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.
(3) De-powdering of interior wall putty powder.
This is related to the amount of ash calcium powder added (the amount of ash calcium powder in the putty formula is too small or the purity of the ash calcium powder is too low, and the amount of ash calcium powder in the putty powder formula should be appropriately increased), and it is also related to the addition of cellulose. There is a relationship between quantity and quality, which is reflected in the water retention rate of the product. The water retention rate is low, and the ash calcium powder (the calcium oxide in the ash calcium powder is not fully converted to calcium hydroxide for hydration) time is not enough, which is caused.
(4) Blistering.
This is related to the dry humidity and flatness of the wall, and it is also related to the construction.
(5) Pinpoints appear.
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.
(6) Volcanic holes 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.
(7) After the putty dries, it is easy to crack and turn yellow.
This is related to the addition of a large amount of ash-calcium powder. If the amount of ash-calcium powder is added too much, the hardness of the putty powder will increase after drying. If the putty powder has no flexibility, it will crack easily, especially when it is subjected to external force. It is also related to the high content of calcium oxide in ash calcium powder, 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 relatively 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 when applying the product in summer, or to increase the amount of cellulose, and to choose a product with a higher gel temperature. 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.
Post time: Nov-26-2022