i dont remember which one of the 8,000 DNP FAQ's i read it in, but one of them claimed that there is a certain chemical in a few liquid detergents that is capable of removing DNP from the skin as well as most fabrics. havent had the pleasure of testing any DNP yet (getting my first 100 gram batch in this friday :woohoo:, so i cant say from experience if its true, but the article used Tide brand detergent as an example of a product that had the DNP killing chemical in it.
worth a try if what is stained means a lot to you... though im sure how long it has had to set will probably be the strongest variable