The factors that cause poor adhesion
Several factors may be causing the poor adhesion and thus the peeling paint. Can be distinguished as the origin, that which comes from the binder and another from the state of the metal itself. For better grip, it should be cleaning the surface to be painted especially for rust because it is one of the main factors that promote the detachmentIn addition to rust, all traces of existing paint must also be removed to allow immediate contact between the new paint and body of steel. And depending on the nature of the latter, it is a primary or not toFor example, if it is emulsion or glycerol, it requires.
For optimum application of paint, a surface preparation must be made and this is reflected in two ways, mechanical and chemical. For the physical cleaning must be equipped with a sandpaper replacement of aluminum silicate and magnesium or size with a layer of zinc less than 10 μ. With the abrasive must be a sweeping motion obliqueIn this stage of physical cleaning, do not violate the metal as for descaling of steel as this can lead to destruction of the galvanized coating. Chemical cleaning is mainly a reflection degreasing can be done with a dilute alkaline solution of ammonia, which will be refined by rinsing.
The model to choose
The choice of the nature of painting defines the mode of application suitable for useIndeed, there is the primary reagent can be done through a gun for a thin layer. This is adequate for sub-layers as they should be covered with special paint and whose nature is compatible with zinc coating. There are also alkyd and glycerophtalic that are commonly used in a conventional manner. Their peculiarity is that the drying is by oxidation followed by formation of fatty acids with the reaction with zinc affects the adhesion. The family of such products is to avoid.
Other models can also be applied as part of a galvanized metal. These include mono-components that can be based binder consisting essentially of polyvinyl chloride or PVC commonly. PVC compounds, acrylic or vinyl are applicable after the degreasing of a galvanized steel.
In addition, there is the type of paint that is two-component epoxy resin based on polyurethane and works well on galvanized steel. But this requires a condition, that make cleaning mechanical scanning angle. Thus, the selection of all these products requires the fact to take into account their effectiveness, their life and their mode of application. |
