Discussing the corrosion, damage, and discoloration of coatings
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Color change or fading is caused by the film-forming substances or by an inappropriate choice of pigments. For example, among film-forming substances, white phenolic coatings can turn yellow, while acrylic coatings will remain white for a longer time. Color change or fading may be caused by whitening on the surface or by damage to the colored pigments. In this case, the pigment is decomposed or degraded as a result of reactions caused by ultraviolet light or chemical conditions. For example, lead chromate yellow gradually degrades and changes color under light exposure, shifting from bright yellow to brownish-yellow. Ferriblue degrades due to reaction with alkalis. Color change or fading can be eliminated or reduced by improving the formulation of the coating. By selecting the film-forming substance and pigments, discoloration caused by powdering can be controlled. Appropriate pigments can provide resistance to light exposure and chemical erosion. Furthermore, the improved and innovative formula should be able to provide a performance balance with a reasonable composition of the coating. Choosing the colored pigments is crucial for the paint formula. A good paint formula may suffer from discoloration issues due to the improper selection of coloring pigments. However, in a chemical environment, corrosion protection of the coating is more important than color resistance.
Discoloration or fading caused by corrosion damage to the coating is usually due to an inappropriate selection of coating ingredients. For example, the film-forming substances themselves may be unstable; white phenolic coatings tend to yellow over time, whereas acrylic coatings can maintain their whiteness for a longer period. Furthermore, pigments can also decompose due to exposure to ultraviolet light or the effects of a chemical environment; for example, lead chromate yellow changes from a bright yellow to a brownish-yellow color when exposed to light, and iron blue fades when it comes into contact with alkaline substances. To solve this problem, it can be achieved by optimizing the paint formula. Choosing the right film-forming substances and pigments, such as those resistant to light exposure and chemical erosion, can effectively reduce discoloration. At the same time, the formulation design must balance various properties to ensure that the coating maintains color stability while providing corrosion protection. However, in a chemical environment, corrosion prevention is usually more important than color stabilization. .