After the base surface is surface treated, the first process is to apply the primer, which is the most basic work in the coating construction process. The purpose of the primer is to create a good bonding force between the base surface and the subsequent coating, to strengthen the foundation, to stabilize the residual dust particles on the base surface, and to seal the moisture and alkali on the base surface to a certain extent. The oil-based primer has a dense paint film and has a good sealing effect on the base surface, but its air permeability is poor. When it is applied to a damp base surface, it is easy to cause the paint film to peel off due to the pressure of underground water vapor. The paint film of water-based primers is not as dense as that of oil-based ones, and generally has a microporous structure, which can release the water vapor pressure accumulated underground, and can also achieve better application results on wet substrates. For example, the two-component water-based epoxy primer has good adhesion to the concrete base surface, and has been widely used in wet concrete base surfaces in recent years.
Correctly selecting the type of primer and its coating process according to the material and surface condition of the base surface can improve the performance of the coating and prolong the life of the coating. Generally, the requirements for the primer used for floor coating are: it should have good adhesion with the substrate; it should have good mechanical strength; The coating creates a good foundation, and cannot contain components that can penetrate into the upper coating film and cause disadvantages; it has good construction and drying properties.
In general, the following points should be paid attention to when applying primer.
①Primers containing pigments and fillers should be stirred evenly before and during use.
② The thickness of the primer paint film is determined according to the type of primer and should be controlled carefully. The coating should be uniform , complete, without exposed bottom, and free of dust and loose sand on the surface.
③Pay attention to observe the drying specifications. When applying a primer such as a paint containing a strong solvent, the primer needs to be completely dry to avoid paint problems such as bottoming.
④ After the surface treatment before painting, the primer should be applied in time in strict accordance with the specified time. It is also necessary to apply a coat of paint within the specified time range after the primer dries according to the conditions specified in the primer variety. Premature coating may cause undercutting and difficulty in solvent volatilization in the primer, resulting in prolonged drying time, poor curing, and bubbling of the paint film; too late coating may cause poor adhesion between layers, and too late coating may cause dust accumulation or other contamination affecting appearance.
⑤ In order to increase the adhesion between the next coat and the primer, the primer can be polished before coating.
The method of coating the primer generally can be rolled, brushed and sprayed. The construction efficiency of brush coating is low, and it is generally used for construction at the corners. Rolling coating is usually used, which has high efficiency.
