Removing rust stains after manipulating old iron pieces is sometimes necessary !
Pour lemon juice with salt directly on the stain. Rub. Then pour slightly wet washing powder and scrub again. Rinse.
If the stain persists, pour some rust remover, available in all supermarkets. Rinse.
You can also expose the stained clothing, linen or cloth over a pot of boiling water while pouring a few drops of lemon juice on the stain. Rinse once with water mixed with ammonia, and finally rinse again with water.