Sometimes the clothes are rubbed with plaster, you can add a few drops of water with alcohol (or sorghum wine), rub it on a place stained with plaster, wait for the plaster to be removed, then rinse with water, or rub it with baked alum powder, and then wash it with water; you can also sprinkle it on the stained area with edible alkali surface, add some warm water, and rub it a few times to remove it. If the alkaline surface is heated in an iron spoon and sprinkled on the stained area, then rub it with warm water to remove the stain faster.