The relationship between putty and latex paint is that of skin and hair. "If there is no skin, there will be no hair." At that time, we proposed the concept of "seven parts of putty and three parts of paint", highlighting the importance of putty. However, many latex paint manufacturers, developers, and construction units do not realize the importance of putty. They mistakenly think that putty is only for leveling and leveling. It is an auxiliary material for latex paint. The production is very simple. A mixer is enough. Stirring, construction is not standardized, I think as long as it can be put on the wall, it can be scraped flat. As a result, there are many problems with the painted surface of the interior and exterior walls, such as the problem of powder removal, cracking, efflorescence, and blooming. problems, yellowing problems, and more. Seriously affected the quality of the project and caused great losses. This series of questions made everyone realize the seriousness of the problem. Especially since building external thermal insulation mortar was popularized across the country, cracks in the finish have become a concern of the contracting party, contractor, construction party, manufacturer, etc. Once there is a crack, the parties will shirk responsibility from each other. According to years of production practice and construction practice, according to the shape of the crack, we can basically delineate the party responsible for the crack formation and provide a good solution.
Cracks in building walls can be roughly divided into four types:
1. Cracks in the wall: The cracks are unevenly distributed with the change of the foundation. Regular crack distribution on the outer wall: it is a horizontal distribution. Peel off the cracks and look again; the above cracks are caused by the settlement and deformation of the wall. The solution: ⑴. If the building has been settling and deforming, don't be busy repairing it. ⑵A variety of solutions should be adopted for repairing according to the shape and density of cracks. It can be repaired by slotting or adding mesh cloth, but it must be repaired with high-elastic putty.
2. Cracks in the stucco layer: the leveling mortar is not flexible enough, and the finish shows relatively large tortoise cracks, which are generally evenly distributed. Use high-elastic putty or two-component flexible putty for a full batch or repair separately. Cracks in the insulation layer: Generally, irregular cracks are more common. It is caused by many reasons such as shrinkage and deformation of benzene board or polystyrene particles, and incorrect construction of mesh cloth and mortar. The solution should be determined according to the size and distribution of the cracks. If it is serious, it is necessary to add mesh cloth and use flexible mortar to press it. If it is not serious, use two-component flexible putty to fill it up or repair it separately. Cracks in the putty layer: generally appear as fine tortoise cracks, which are evenly distributed. Note that it is not a seam or a grain, and there is a difference between a grain and a seam.
Below we mainly talk about the cracking of the putty layer. If the putty coating is too thick, cracks will occur. Generally, the thickness of the putty is 1-2mm, and generally not more than 3mm. Some interior and exterior walls have an error of as much as 3-5 cm in the flatness of the base surface. If they are all leveled with putty powder, they will definitely crack. Mortar should be used for leveling. The larger the error, the coarser the sand of the mortar is required. The base layer should be leveled with masonry mortar, and the flexible mortar should be used for leveling. If the amount of inorganic binder (ash calcium powder, cement) is too much, the strength will also cause cracks. Generally, cracks appear in the waterproof putty of the inner and outer walls. If the amount of lime calcium powder and cement added exceeds 50%, the strength of the putty will be too high, the finish will be hard and brittle, and cracks will easily occur. In the past, glue was used in most areas of our country (not 107 glue, because 107 glue was discontinued due to environmental protection issues), plus old powder or glue for exterior walls plus white cement, it is easy to cause powder removal and cracking. The plaster layer of the inner and outer wall base is loose and dusty. If it is not resolved, the full batch of putty will bond a layer of powder on the surface, which is easy to bulge and layer. If the sound is different when it is knocked by hand, cracks will appear slowly with the change of external cold and hot temperatures, and the cracks will open in a hollow place. If you open the crack, you will see that there are two layers of putty and the bottom of the wall, and a layer of dust in the middle. The putty layer is not tightly combined with the stucco layer, the bonding strength is not enough, and the cracks are bulging.
