Q & A on common symptoms of wall paint

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Some problems in wall paint are also common, some because of environmental impact, some because of improper construction. Cracks and mottled walls are a great eyesore. Is there any way to remedy it? The so-called remedy to the case, the root causes of various wall symptoms are different,

some problems in wall paint are also common, some because of environmental impact, some because of improper construction. Cracks and mottled walls are a great eyesore. Is there any way to remedy it? The so-called right medicine, the root causes of various wall symptoms are different, so the treatment is also divided into different situations

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I. what is the reason for the pathological film

the pathological condition of wall paint can occur before, during or after the construction of the paint. Understanding the factors that cause the pathological condition of the paint and film is helpful to take targeted preventive measures. The causes of the pathological condition mainly include the following aspects:

1. The quality problem of the wall finish itself: the base material used for wall paint and its properties, the ratio of the base material to the color and filler, Fineness of pigments and fillers, selection and dosage of additives in the base material, etc

2. Construction base condition: base material, construction procedure, surface roughness, humidity and acidity of base material, maintenance period and quality of putty used for base material treatment

3. Coating process: thickness of coating, construction procedure, whether there is primer and topcoat matching, recoating interval, etc

4. Construction operation: before construction, whether the paint is stirred evenly, whether it is diluted arbitrarily, whether the construction machinery or operation is normal, whether the personnel are skilled in construction technology, etc

5. Construction environment: the climatic conditions during construction and the conditions of the construction site, such as temperature, humidity, whether it is windy or rainy, etc

II. Why does wall paint have sagging? How to overcome

paint diseases such as sagging and flowing sometimes occur in the construction of wall paint. The reasons are as follows:

1. The viscosity of the paint itself is too low, or the water is too little

2. The paint is too thick, and the sagging or flowing is directly proportional to the thickness of the film

3. The paint contains more dense pigments and fillers

4. The humidity or temperature of the construction environment is too high or too low

5. The spraying distance is too close or the paint is not stirred evenly before mixing

to avoid sagging and flowing, the following preventive measures can be taken:

1. Ensure that the viscosity of the coating is moderate and reaches the construction viscosity. Generally, it should be more than 25 seconds (when airless spraying is used for wall paint, water or even no water can be added)

2. Control the thickness of coating. The film thickness is generally controlled at 20-25um (dry film)

3. When designing the coating formula, do not use too many pigments and fillers with high density

4. The temperature of the construction environment should be kept above 50 ℃, and the temperature should be less than 85%

5. Before coating, the coating should be stirred evenly, and the technical level of construction operators should be continuously improved to ensure the coating quality

3 Why does wall paint sometimes change color or fade? How to prevent

if the coating film of wall paint is often exposed to the natural environment and subjected to wind, sun and rain, the coating film will change color and fade over time. If the overall surface of the building is uniform, even if the discoloration or fading is serious, it is easier to be accepted by people than local fading

the discoloration and fading of the film are usually related to the base material and pigment. Some organic pigments have poor light resistance and are not alkali resistant. Under the action of sunlight, chemicals and air pollution, the pigments will change qualitatively. The chalking of some pigments will also cause the coating to fade, such as the chalking of anatase titanium dioxide. The yellowing tendency and poor weather resistance of the base material will also cause discoloration and fading. When designing the formula of exterior wall paint, we must choose the base material and pigment with good weather resistance, such as pure acrylic lotion, styrene acrylic lotion and rutile titanium white, iron oxide series and titanium cyanine series pigments. This is very important to avoid or reduce the discoloration and fading of the film. This is also the reason why the base materials and pigments used for interior and exterior wall finishes are different

IV. what is the reason why the paint on the wall sometimes has a scratchy coating and uneven color? How to overcome

there are many reasons for the blooming and uneven color of the wall paint film, which are not only caused by the paint itself, but also affected by factors such as construction and substrate surface. This is the most common and troublesome problem in the construction of architectural paint

1. It has floating color. The final color of the paint is high-profile and produced by a variety of pigments. Each pigment particle floats on the top, and the dense pigment particles gather at the bottom, resulting in color separation. Although fully stirred, the coating is still prone to color differences after drying

2. The pigments in the paint are not dispersed well, or more than two kinds of pigments are mixed unevenly with each other. The dispersion of pigments is not good or the density difference is too large. During brush coating or roller coating, stripe color difference occurs in the direction of brush and roller, that is, floating color occurs. In addition, after the film is dried, the pigment particles are unevenly distributed due to their floating, resulting in floating spots

3. Uneven painting during construction. Uneven painting thickness and unskilled construction will also result in different colors

4. The surface roughness of the base course is different. The base material is too alkaline, and the absorption of the applied coating is uneven, which is also easy to cause uneven color. When the covered part of the scaffold is sprayed or brushed with paint again, the coating amount and paint color may be different from that of a large area, which will also cause uneven color

in order to overcome the phenomenon of wall paint film blooming and uneven hue, the following preventive measures can be taken:

1. Select appropriate pigment dispersant. It is best to use organic and inorganic dispersants together to keep the pigment in a good and stable dispersion state

2. Improve the viscosity of wall paint. If the viscosity is too low, the floating color phenomenon is serious; If the viscosity is high, the delamination tendency will be reduced even if the pigment density is relatively large

3. Mix fully before construction to make the coating uniform without floating color or sedimentation. During construction, do not dilute with water at will

4. Try to be uniform during construction and stack strictly according to the operation. The film should not be too thick. The thicker the film is, the more likely it is to appear floating color and blooming

5. In order to make the base absorb coating evenly, it is best to apply paint sealing primer

6. When repainting or brushing the covered parts of the scaffold, it should be done carefully, and the coating amount should not be less than the specified amount. Try to use the same batch of paint to ensure that the overall finish color is consistent

v. why does the wall paint film sometimes crack

the base material of wall paint is different types of lotion, and each wall paint has a corresponding minimum film-forming temperature. If the construction is carried out at a lower temperature in order to rush the construction period, and the film-forming temperature of the lotion cannot be reached, the lotion cannot form a continuous film, resulting in cracks in the exterior wall coating

improper treatment of the base, such as the cracking of the cement wall, will also cause the cracking of the coating. Due to the different drying speed of wall paint, when the primer or the first coat is too thick and not completely dry, the surface layer or the second coat is applied, which is easy to cause the film cracking. In order to avoid this phenomenon, the construction under the climatic condition of lower than 50c should be avoided first. If the construction temperature is low, the amount of lotion film-forming additives should be increased, and general additives should not be used

in addition, it is better not to use cement putty to deal with the base course

the thickness of the coating shall meet the requirements of process operation. The primer layer or one coat of paint must be completely dry before applying the finishing coat

VI. what are the reasons for the peeling and peeling of the wall paint sometimes? How to prevent

1. The wall paint itself does not form a good film, that is, the lotion does not form a continuous transparent film, resulting in cracking, which will fall off in cold water

2. The content of pigments and fillers in the coating components is too high, and the resin content is too low, resulting in poor adhesion of the film

3. The base course is loose, with dirt such as floating dust and oil, and the adhesion between the film and the base course is poor

4. The adhesive strength of the putty used for base leveling is low, and the coating is applied before the putty layer is dry

5. The substrate is too smooth, which is easy to cause poor adhesion of the film

in order to prevent the peeling and falling off of the wall paint film, the following preventive measures can be taken:

1. The construction temperature should be above 50c, and the film-forming additives should be properly selected and added in an appropriate amount to ensure that the wall paint forms a continuous film

2. Choose the appropriate color to base ratio according to different application occasions and requirements, and do not increase the amount of color and filler too much to reduce the cost

3. Handle the base course well, shovel off the loose layer, and clean up the milk dust and oil dirt

4. According to the different requirements of interior and exterior walls, choose putty with good bonding strength. The putty layer should not be too thick (subject to leveling the wall). Be sure to wait until the putty is dry before coating

5. The too smooth substrate should be treated with interface agent to enhance the adhesion of the coating and reduce the falling off

VII. Why are the coating cracks and peeling off easily on the walls and ceilings of kitchens and bathrooms

cracking, peeling and falling off of the coating on the walls and ceilings of kitchens and bathrooms in general families, especially bathrooms, are very common. This is not only related to the performance of the coating itself, but also closely related to the water resistance of the putty used

in China, cellulose white putty or gypsum putty is mostly used in the treatment of inner wall base at present. The function of putty is mainly to level the wall, without any specific technical requirements. However, the water resistance of these putty is very poor, especially the cellulose white putty. The cellulose expands with water and gradually dissolves in the water. Due to the increase of volume and the decrease of bonding strength, the coating bubbles, cracks and falls off. To solve the above problems, water-resistant putty must be used, together with special paint for kitchen and bathroom or latex paint with good performance. It is recommended to use matching putty

VIII. What kinds of putty are commonly used for wall paint

according to the construction and acceptance specifications of Building Decoration Engineering, the interior wall decoration should use putty to smooth the wall before coating. The putty matched with the wall paint includes cellulose white putty and gypsum putty. Sometimes, in order to improve the strength of the putty, a part of lotion is added to the putty. The putty used in kitchen, bathroom and bathroom is water-resistant putty, which can further show the characteristics of supporting paint. It is recommended to use supporting putty

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