You know there is a company that uses red clay to dye their clothes...It is very hard to get out I've lived in the land of red clay all my life when I would take my kid to buy new shoes, all of the socks I could see were dyed red...even the kids had red skin. The only suggestion I can offer is to use any product but leave it on longer and rub the stained fabric against a slean patch. Good luck. You would be amazed at what you can do with stained clothes to reinvent them. Oh, and some fabric protection, ie. silicone or another stain repellant can help, pre stain. If all fails, tell people the stain happened when you were saving a child from an alligator...