I just " test" a snippet of something that I think may bleed in a cup of hot water.......and so far so good, but I tend to stay away from red, navy, dark intense colors......the article, in my opinion, is a bit of overkill....soaking for 12 hours! Maybe if one is dying fabric....which I would never do, nor do I purchase any "hand dyed" fabric.........but we do what we do