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1. Acids: Inorganic acids primarily cause the hydrolysis of certain polar groups in the polymers that make up the coating; they also undergo addition reactions and isomerization at double bonds. Furthermore, they can dissolve and break down the pigments and additives present in the coating, ultimately causing the coating to lose its protective function. Organic acids accelerate the progression of harmful reactions by also having swelling and dissolving effects on polymers, thereby intensifying the erosion. 2. Bases: The main function of alkaline solutions is hydrolysis; they also form salts with the acidic groups in polymers, making the coating more hydrophilic and even causing it to swell and soften. 3. Salt: The damage caused by salt solutions lies in the increase in ion concentration; the penetration of these ions leads to a decrease in the resistance of the coating. Some ions, such as chloride and sulfate ions, can also interfere with the function of corrosion-inhibiting pigments at the bottom of the paint film, thereby promoting corrosion of the metal beneath the coating. In terms of the stability in corrosive media, carbon-chain polymers are superior to hetero-chain polymers ； It is better when the hydrogen atoms on the carbon chain are replaced by fluorine or chlorine atoms (such as fluororesins) ； A higher saturation level and lower polarity are better than having more polar groups containing double bonds.