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    Home > Coatings News > Paints and Coatings Market > Exterior paint film cracks! How to solve and avoid?

    Exterior paint film cracks! How to solve and avoid?

    • Last Update: 2021-01-05
    • Source: Internet
    • Author: User
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    China Paint Online News
    In this era of pay attention to the value of the face value, whether it is indoor coating or exterior wall decoration, we will use architectural paint to decorate and protect the wall, protect the building wall, improve the life of the wall, while improving its aesthetic value. However, it is not difficult to find that many buildings after completion of a short period of time will appear cracking, color change, foaming, peeling and other issues. Most of these problems arise because the quality of products is not pass, or construction technology is not pass. So, when the paint film cracking situation, how to solve or avoid these problems? As a senior portal in the industry, China Coatings online

    small editor
    for you to propose good solutions., the cause of cracking of exterior paint
    1, the cracking of the grass-roots. The base of the exterior coating finish is the cement mortar ash layer, which will produce dry shrinkage and temperature difference contraction in the condensation process, and if the external wall dust construction operation is not proper, it is easy to cause empty drums and cracking. Before the construction of the coating surface do not pay attention to repair and then enter the next process, after a period of sun wipers, the internal cracks will gradually develop outwards, and the paint film is very thin coating surface is difficult to offset this internal stress, it will follow the cracking.
    2, putty layer cracking. Because of the defective quality of the putty used in the outer wall, the crack resistance is poor. Or due to improper construction operation, putty batch scraped on the wall because of dry shrinkage, cracking and thus affect the coating surface.
    3, coating surface cracking. Some coatings with quality problems due to poor cracking resistance, or due to improper construction, painted on the wall soon, after the wind and sun easily appear dry cracking and other quality problems., prevention and solutions(a) material selection
    1, dusting the cement used at the grass roots. It is best not to choose the condensation time too fast early strong cement, in order to avoid the cement mortar too fast condensation dry shrinkage caused by cracking phenomenon, sand to choose qualified river sand, particle size should not be too fine, in order to sand the best.
    2, the choice of outer wall putty. At present, there are many kinds of external wall putty products in the building materials market, all marked with excellent cracking resistance, must be carefully selected, as far as possible to choose a brand or large factory production of special anti-crack flexible putty products. After the start of the project can choose a number of products that meet the standards, make putty base model, after several months or more of observation, in the project is about to enter the external wall decoration construction, can generally compare which product cracking performance.
    3, the choice of exterior paint. First select a few different brands of qualified products, early to make a model, through observation and comparison to make a choice. In addition, it is recommended to choose thick anti-cracking exterior paint, such as elastic brush, embossed paint and other types of paint, because its coating thickness is more than 5 times the ordinary paint, through the construction practice found that can effectively offset the cause of the grass-roots cracks caused by the paint finish cracking, of course, its price is higher than the general flat coating products.(ii) the construction of the mortar surface layer of the outer wall
    1, the ratio of cement mortar used to dust the outer wall to choose the appropriate, generally using 1:2.5 mortar is appropriate, try not to use 1:1 or 1:2 cement mortar.
    cement is too large, the mortar shrinkage is large, easy to produce cracks. In order to facilitate the construction, can be appropriately mixed with powder ash, or added glue (e.g. 107 glue, etc.) to increase the consistency of the mortar, improve the adhesion of the ash mortar and the wall, can prevent empty drums, cracking. In addition, by adding Dura fiber (0.7 kg of Dura fiber per m3 cement mortar) and appropriate amount of glue in cement mortar, the construction practice found that it can effectively enhance the cracking, impermeability and wear resistance of the mortar surface layer, which can enhance the delay, anti-cracking strength, and the increased cost is not large.
    2, in strict accordance with the external wall ash operation procedures and process construction, before the dust must be carefully removed from the grass surface dust, dirt, oil stains and brick wall ear ash. The day before the construction must be watered through the wall, after the completion of the construction of 24h, must be watered maintenance, the number of watering times per day should be determined according to climate conditions, at least twice a day, maintenance time is not less than 7d.
    3, brick wall and concrete beam column combination, easy to produce cracks, should be used at the combination of nail wire mesh riding seam method to enhance the crack resistance of the mortar, can prevent the appearance of cracks. For the smooth part of the concrete beam column, the cement is scraped with 107 glue pulp to increase the bonding ability between the mortar and the smooth base, and prevent the mortar from appearing empty drum and cracking.
    4, such as in sufficient sunshine season construction, should be scientifically arranged construction time, to avoid the sun in the construction, or take effective sun protection measures to ensure that the mortar surface of the yin dry, to prevent the dust mortar layer due to the sun too fast drying caused by cracking.
    5, cement mortar ash surface layer should not be too large, make full use of the subgra seam can adjust the contraction of cement mortar. According to experience, the split within the 2m range can effectively reduce the appearance of cracks. In the construction of the use of triangular or trapezoidal cross-section of the wooden strip, cement mortar surface layer for the division, the same construction section is not allowed to appear construction seam joints, the split seam should have inlay paste seam.construction of the outer wall putty layer
    1, the construction of the outer wall putty layer should be carried out after the ash layer has reached the maintenance period.
    2, putty batch scraping should be the dust mortar layer inspection, the appearance of empty drums, cracks in the site 2 to 3d in advance to repair. Remove dust from the dust and sand from the dust surface and keep the dust layer clean.
    3, strictly in accordance with the requirements of the construction specifications and product description construction, to ensure that putty layer and dust layer bonded firmly, not cracked. At the same time, the construction to avoid sun exposure work, to ensure that the putty layer in a dry state.
    4, putty layer after the completion of the grinding process should be timely maintenance, and at the same time wash away the powder generated by grinding, so that the wall clean, in order to enter the paint surface construction.(4) The construction of the coating surface layer
    1, before the construction of the coating surface layer, we should ensure that the putty layer is flat, solid, clean, no crisps, powdering, peeling and other defects, such as the inspection should be timely repair if found defects.
    2, according to the paint finish construction specifications and paint product requirements, putty base moisture content of 8% to 10% or less can be painted coating construction. The drying of putty base in construction is the key to ensure that the coating surface layer is firmly bonded and does not crack. Therefore, it is strictly prohibited to catch up with the work period does not wait for the putty layer to dry out after the forced construction.
    3, paint surface according to different functions, the use of different materials divided into several layers of brushing, the last layer of brushing construction must ensure that the previous layer of paint film surface dry and then carried out, at room temperature each interval of 2 to 4h, the construction environment temperature should be above 5oC. Each paint film before painting to carry out a careful inspection of the previous process, confirm qualified re-construction.
    4, according to the construction process and product requirements, the grass-roots ph value is required at less than 10. Therefore, the construction must first be painted with an anti-alkali primer, its anti-mold, antibacterial, anti-acid and alkali performance is good, the putty layer penetration is strong, can fully ensure that the coating layer and putty layer bonding firmly.
    5, coating surface construction, shall not be carried out in the wind 4 or above, or rainy days, foggy days and relative humidity of more than 85% of the environment, to prevent high winds from dust pollution paint, as well as to ensure the drying of the construction surface. Work should also be avoided in hot sun or hot weather.
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