1. Wipe the stain with 15% acetic acid solution (15% tartaric acid solution is also acceptable), or soak the contaminated part in this solution, and then rinse it with clear water the next day.

2. Moisten the contaminated area with 10% citric acid solution or 10% oxalic acid solution, then soak it in concentrated brine and rinse it off the next day.

3. The fabrics of white cotton and mixed cotton are stained with rust. Put a small grain of oxalic acid (available in pharmacies) on the stain, drop a few drops of warm water, gently rub it, and then rinse it with clear water. Pay attention to quick operation to avoid corrosion.

4. The simplest method: If there is fresh lemon, squeeze out its juice and drop it on the rust, rub it by hand and repeat it several times until the rust is removed, and then wash it with soapy water. The most effective method is oxalic acid. Firstly, oxalic acid is dissolved into solution, and clothes are soaked in water. Drop oxalic acid solution where there is rust. After a while, the rust will disappear, and then the clothes will be washed several times. As good as new, it's not obvious at all.