The real stone paint on the wall soon turned white. How to remedy it?
How to solve the problem of white real stone paint?
1. Check whether the base of the real stone paint turns white due to less or missed alkali resistance primer. If it is due to the whitening of pantothenate, the project must be redone, otherwise, it can only be reworked.
Composition of real stone paint
1. Alkali-resistant primer, 2. Main material of real stone paint, 3. Self-cleaning finish paint
The real reason why the real stone paint turns white?
When the temperature is high in summer, the whitening phenomenon of the real stone paint is rare. It usually occurs in winter. In rainy days, when it rains for several days in succession, the surface of the real stone paint just constructed will become a comprehensive whitening phenomenon one by one. Especially when the temperature is below 10 ℃ and the humidity is above 85%, the appearance of the real stone paint will turn white or look like fading and blossoming, as if it is obscured by a layer of white ice.
Analysis of the causes of whitening of real stone paint
The construction environment temperature and vitrification film forming temperature elements, emulsion film forming temperature, that is, emulsion vitrification temperature (except elastic emulsion), are all above 26 ℃. When the temperature is higher than or equal to the vitrification temperature, emulsion can be completely cured, and only when emulsion is cured can emulsion give play to its waterproof performance. However, when the air temperature is lower than the temperature of emulsion, the film-forming time of emulsion becomes longer, but when the temperature is lower than 10 ℃, the emulsion is relatively "fresh", and the emulsion cannot be completely cured, but can only be dried. When the temperature drops below 5 ℃, the real stone paint in the barrel may also be frozen. That is to say, when the temperature is lower than a certain value, the real stone paint cannot be applied, so it is not difficult to explain why there are so many complaints about the whitening of the real stone paint in winter.
Selection factors of raw materials
A. Selection of emulsion
Styrene acrylic emulsion, as we all know, after soaking in water for a long time, the styrene acrylic emulsion is 100% white, and the immersion time may be longer in summer. Pure propylene or silicon propylene is better than styrene-propylene. However, when the temperature is too low and the construction is not completely dry, it will encounter cold winter and rain, and the best formulation of real stone paint will also face the whitening risk. The test shows that under the cold temperature below 4 ℃, the better silicone acrylic lotion is selected for the same test, and the stone like paint is still white. Therefore, environment and climate are important factors for the whitening of real stone paint.
B. Selection of additive
1. Cellulose is a hydrophilic thickener, which is much better for construction and preservation when added, but the waterproof property of real stone paint will be weakened, resulting in the appearance of whitening.
2. The addition of alkali thickening has a good can opening effect on the stone like paint, but the waterproof degree of the stone like paint decreases accordingly with more use. After the surface of the stone like paint becomes dry, the alkali thickening will gather on the surface of the stone like paint and form a film with the emulion, because the hydrophilic property of alkali thickening is extremely strong, which will seriously reduce the waterproof degree of the emulsion, and make the surface of the stone like paint whiten more simply.
3. The addition of film forming additives and antifreeze makes emulsion survive in the deep winter. It increases the stability and antifreeze of emulsion, reduces the glass transition temperature of emulsion, and prolongs the drying time, but it is obvious that the waterproof degree decreases, and also increases the probability of stone paint whitening.
Solution to whitening of real stone paint
1. Air temperature and environmental factors: when the air temperature is lower than 10 ℃, construction should not be carried out as much as possible. If construction is required, do not select rainy weather within 5 days before and after construction. It is necessary to spray water-based finish paint after the stone paint is completely dry.
2. The key formula of stone like paint is the right emulsion, and the additives are added properly. Try to find the non hydrophilic additives. The hydrophilic additives should properly do more data in the laboratory to find the critical point for the addition of emulsion additives.
3. Avoid jerry-building: it is necessary to apply the alkali resistant primer and keep the base completely sealed. If the missed coating is soaked in the rain and alkalized to form white, the real stone paint will fail to cut the bottom and form an irreversible situation. It is necessary to eradicate and re-construct.
4. The intermediate coating of the real stone paint cannot be sprayed less, because the natural sand mesh in the real stone paint is relatively thick and has no covering power, so it is necessary to completely cover the impermeability when spraying, which is about 4-5kg/m2 (medium thick type), and the waterproof finish can not be sprayed less. It is better to select the water-based finish, which is not only environmentally friendly but also useful for water permeability.
Precautions for construction of real stone paint
1. When selecting putty, it is better to choose black putty powder, which has low alkalinity and is easy to neutralize after maintenance.
2. After the putty is dried and polished, it must be maintained with water to neutralize the alkalinity of the putty. If the putty is too alkaline, the alkali-resistant primer is also difficult to resist, so water maintenance and alkalinity is the key.
3. Make enough primer and finish.
4. Construction shall not be carried out in the environment with low temperature and high humidity.
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