How to Wash Off Hardened Lime Stains on a Car?
2 Answers
Hardened lime stains on a car can be cleaned using white vinegar or diluted hydrochloric acid. Here are the relevant details: 1. Lime powder: Since lime powder is alkaline with a pH greater than 7, acidic substances can be used to neutralize it. The chemical formula of lime is Ca(OH)2, which is a mixture containing calcium hydroxide Ca(OH)2. When exposed to CO2, it becomes turbid, forming water-insoluble CaCO3 (calcium carbonate) and H2O CaCO3 + 2HCl = CaCl2 + H2O + CO2. Therefore, if lime stays on the car for a long time, it can indeed be difficult to remove. 2. Cleaning principle: After being exposed to air for some time, lime transforms into calcium carbonate, which is insoluble in water but soluble in acetic acid or diluted hydrochloric acid. Hence, white vinegar or diluted hydrochloric acid can be used for cleaning.
A few days ago, my car also got lime stains that dried up and became rock hard. At the time, I tried rinsing it directly with water but couldn't remove it. I suggest first covering the lime with a wet cloth and waiting about ten minutes to let the water soak in and soften it. If the lime is alkaline, apply some white vinegar to neutralize it—don't rush to wipe it by hand, as this could scratch the paint. Once the lime softens, gently wipe it off with a soft cloth or sponge, repeating the process until it's clean. Afterward, rinse thoroughly with clean water twice; otherwise, vinegar residue may leave marks. If there's slight corrosion on the paint, applying some car wax can help protect it. Usually, try to avoid parking near construction areas. If this happens again, early treatment works best—if delayed, professional car washing may be necessary.
