Ventilation and drying: 1. The new cement mortar and concrete surface need to go through a period of ventilating and drying maintenance period to allow the wall to be fully dried so that the water content of the wall is less than 10% and the PH value is less than 10 before construction. Generally, cement mortar walls should be dried for more than 7 days at 25 degrees and a relative humidity of 65%, and concrete walls should be dried for more than 21 days. 2. Paint for cast-in-place or precast cement concrete substrates requires a longer curing period and thoroughly remove the surface release agent.
Analysis of the construction process of water-based coatings. Water-based coatings have particularly high requirements for the cleanliness of the painted surface. Therefore, the surface treatment before painting is particularly important. In addition to the normal steel pretreatment, the surface must be thoroughly cleaned before painting. White corundum, etc. sandblast the surface of the car body to remove all dirt such as oil and dust on the car body surface. It is also possible to pre-coat a solvent-based paint before the water-based paint is painted. Generally, the pre-painted solvent-based paint selects fast-drying and good adhesion paints, such as alcohol-soluble vinyl phosphate primer. Good stain resistance: Due to the large differences in environmental conditions in different regions of our country, for some cities with developed heavy industries and mining, due to the large amount of dust and other suspended substances in the atmosphere, the easily stained coating will lose its original decorative effect. Thereby affecting the appearance of the building. The exterior wall coating has good stain resistance, so that the coating is not easy to be contaminated or easily cleaned after contamination. Good water resistance: The exterior wall paint finish is exposed to the atmosphere and will often be washed by rain. Therefore, the exterior wall paint coating has better water resistance. Good mildew resistance: exterior wall paint finishes are prone to mildew in humid environments. The coating should inhibit the growth of mold and algae.
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Analysis of the construction process of water-based paint and the difficulties and solutions in the painting process. After the car body pre-coating primer is dried, apply the water-based paint. Use a 65:1 airless sprayer and adjust the air pressure to 0.3～0.4MPa , The nozzle is 25P25, and the tank car body is painted wet-on-wet in two passes. The coating thickness is required to be no less than 80μm, and the interval between the two passes is 20-30min. In the meantime, check the coating film to see if there is any paint film defects such as flow or missed coating. Use a brush to smooth the flowed area and recoat the missing part. The second painting is the same as the first painting. If there is a small amount of sag, it needs to be gently smoothed with a paint brush immediately. drying. The car body should be dried after painting when the temperature is lower than 15℃, cloudy and rainy days or need to leave the workshop immediately. The drying temperature should be around 60℃ for 0.5～1.0h. After the black water-based paint is applied, the coating film is grayish green, and after drying, it becomes black without gloss. Other corrosion-resistant materials mainly have a series of problems such as insufficient strength, limited service life, and poor economy.
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Difficulties and cracks in water-based paint coating: mainly occurs when water-based paint and solvent-based paint are matched. If solvent-based paint is dissolved in the water-based paint coating in the later construction, it is prone to cracking. Analysis of the construction process of water-based paint and the difficulties and solutions in the painting. Solution: When spraying solvent paint, it is necessary to protect it to prevent the solvent paint from flying to the part to be sprayed. Shrinkage: Water-based paint uses water as the medium. When the surface to be painted is not cleaned and there is dirt, because the surface tension of water is large, it is easy to cause shrinkage. Solution: Thoroughly check the state of the surface to be painted, and if necessary, use sandpaper to roughen the surface of the primer to make it have a certain degree of roughness, which is conducive to the painting of the top coat. Drop cracking: In thick coating, when the wet film thickness exceeds 120μm, drop cracking is easy to occur. Solution: Use multiple spraying methods to meet the specified requirements. The time interval between each spraying should not be less than 5min, and the film thickness of each spraying should be controlled within 30-40μm (dry film). For various decoration projects such as residences, public buildings and industrial buildings, thick acrylic copolymer emulsion external wall coatings (including multi-layer, sand-like external wall coatings) can be used. For various decoration projects that require high stain resistance and weather resistance, solvent-based organic silicon modified acrylic resin exterior wall coatings and solvent-based fluorocarbon resin exterior wall coatings can be selected. The above is the relevant information about how to use exterior wall coatings and how to choose exterior wall coatings introduced by the editor today. Whether it is thin or thick exterior wall coatings, especially water-based exterior wall coatings, they generally need to be sealed. . Choose different types of sealing primers according to the specific conditions of the substrate. In the next 5 years, the water-based rate of industrial coatings in my country will increase from the current 15% to more than 50%. Some research institutions also predict that the proportion of industrial coatings water-based may double in the next three to five years.