Old, dried-in and so-called ‘burnt-in’ stains due to incorrect washing are much more difficult to remove than recent ones. Therefore, we recommend you not to leave soiled linen lying around but to put it to soak immediately. Dried-in stains with a high level of tannin (from wine or fruit) can become darker with time. Special cleaning agents should be used for this particular type of stain (tannin remover).