01
Pulverization - commonly referred to as "powder dropping"
Features: there is a thin layer of powder on the surface of the wall paint film, the clothes will turn white when they are touched, and they will fall when they are wiped.
Causes:
● add excessive water to dilute during construction, resulting in too thin paint film. (the common contractor materials appear to save materials)
● the wall base is too alkaline (pH value is greater than 7-10), and the paint film is damaged. It usually occurs on the new wall surface of the putty that is not dried thoroughly
● high humidity of wall base and environment, short recoating time and poor ventilation
● the base of the wall (such as the bottom putty with inferior materials) is too loose
● the film is not fully formed during painting, generally, it can be fully formed 7 days after construction
● use interior wall paint for outdoor use.
● bought fake and inferior products
resolvent
The powdered layer shall be removed, the powdered materials shall be cleaned, washed with water, dried or applied with building adhesive.
It is not suitable to construct when the wall temperature is lower than 8 ℃.
The amount of dilution water shall be appropriate, and it shall be adjusted according to the concentration of paint, and excessive dilution is not allowed.
When necessary, appropriate primer shall be selected to carry out alkali and moisture-proof sealing treatment on the wall base, so as to improve the adhesion of the top coat.
It is recommended to apply two coats of interior wall coating with good weather resistance.
02
Uneven surface gloss of paint film
Features: uneven luster of wall paint film, light and shade distribution, often appear in mercerized and semi gloss wall paint products.
Causes:
● uneven porosity of wall base.
● the painting thickness of primer and finish is uneven.
● there is dry spraying in local application during spraying.
● use different construction tools for the same wall.
● different products are used for the same wall.
● failure to connect the brush mark gap when the paint is wet, resulting in obvious joint mark, that is, failure to effectively "wet connect".
● the wall base temperature is too high, or the putty quality is poor, loose, and the paint drying is too fast.
resolvent
The primer, especially the local repair, must be applied together with the surrounding area, and then the top coat.
No matter primer or finish coat, ensure that the thickness of each layer is the same and there is no missing brush.
○ ensure the use of uniform construction tools. Use the same product on the same wall, and ensure the wet connection in the grid area.
Select appropriate concentration according to different climate to adjust the drying time of paint.
03
Blistering of wall paint surface
Features: there are many irregular protrusions on the surface.
Causes:
● the moisture content of the base course is too high and not fully dried.
● when the primer is not dry, apply the finishing coating.
● when spraying, there is water vapor in the compressed air, which is mixed with the coating.
resolvent
The base course shall be fully dry before painting.
After the bottom coating is completely dry, the top coating shall be applied.
Check the oil-water separator to prevent water vapor mixing before spraying.
○ after the foam wall is completely dry, use fine sandpaper to gently smooth the bubble, and then paint. For large area of air bubbles, wipe them out and repaint them.
04
Wall hanging
Features: the film is partially drooping, forming a tear like or corrugated shape.
Causes:
● the construction surface is too smooth or uneven, and there is oil accumulation in the concave part.
● the paint is excessively diluted by water and the viscosity is too low.
● too many materials are dipped in the roller and brush, and the paint film is too thick for one time.
● the spraying pressure in the spraying construction is uneven, and the distance between the spray gun and the construction surface is inconsistent.
● paint drying is too slow.
resolvent
Sand the wall surface to increase adhesion. If it is a base course, uneven, should use the base course as far as possible to level and grind off the edges and corners. When brushing, brush hard.
Improve the construction technology, paint several times more, and apply thinly each time.
The dilution water shall be added in proportion according to the concentration of the paint and shall not be excessively diluted.
In the spraying construction, adjust the air press to make the pressure uniform, adjust the distance between the spray nozzle and the coating surface enough to eliminate this defect, and move evenly.
05
Surface pantothene
Features: salt and alkali precipitate on the surface of the paint film, forming white sagging on the surface or damaging the adhesion of the paint film.
Causes:
● the moisture, alkali or salt content of the wall base is too high. When the water vapor volatilizes, the salt and alkali will be brought out and precipitated on the bottom or surface of the paint film.
● poor waterproof treatment during civil engineering causes rainwater to enter into the base on the other side of the wall through cracks or unpainted base surface, which will bring out salt and alkali during diffusion.
resolvent
Remove the powdered layer;
Select appropriate paint;
○ follow construction specifications and do not over dilute;
When necessary, appropriate primer shall be selected to seal the wall base;
Ensure that the construction environment meets the construction requirements.
Source: the article is transferred from the Internet, we respect the original, reproduced for better communication, occasionally changed, we can find the author and source. For copyright and other reasons, please contact us!
This is the official account for building materials people.