The construction of the wet base is extremely troublesome and outweighs the gains. It is rarely used in developed countries. There are also strict requirements under special circumstances. In our country, such violations of conventional practices are often taken for granted in order to keep up with the progress of the project.
The architectural coating should have good adhesion on the base layer. This kind of adhesion is basically dependent on "adhesion". The adhesion is produced by various gravitational forces between the surface of the base layer and the polymer material, such as chemical chain force, intermolecular force, and interface electrostatic attraction. The most classic theory is Relying on the combination of mechanical forces, that is, the polymer in the coating penetrates into the interior of the base layer, and after curing, the meshing force is generated in the interface area to achieve the effect of "rooting"
There is no standard for the moist base layer, some even call the saturated water-absorbing base layer. When the solid surface is covered with water molecules to form an isolation layer, the polymer material cannot root on the base layer or generate gravitational force with the solid molecules of the base layer. Strong adhesion is bound to be easy to peel and peel off. The application of water-based paint on the wet base layer can prevent premature filming, but this "wetness" has a limit. Many materials indicate that a dry mop needs to be used to absorb the excess water from the base layer. Even so, the "hard drying" of the paint should include the hard dry base layer. meaning. Only reliable adhesion. In addition, water vapor is enclosed within the grassroots level, and there is always a way out, otherwise it will be sealed for a while, and it will not last for a long time. The hidden dangers are self-evident.
Some coatings undergo a moisture curing reaction on the wet base layer. The moisture content of the base layer does not mean that it can be infinitely closed. It needs to have theoretical basis and experimental demonstration. In principle, except for underground waterproofing and certain waterproof constructions, Architectural coatings should prevent the base layer from being applied in a damp state.