My brother and I bought the clay bath kit to try it out for metal d-tox. He took a bath last night and is letting the water run out of the tub slowly. We can see some very black clay at the bottom of the tub and a black ring around it also. According to the website at www.magneticlay.com, the clay turns black when the mercury comes out of your body. We are very excited about seeing it, but my brother, who is a biology teacher wants to do a control bath next to see if that clay turns black too. He is going to do the exact same thing (mix clay with water in the tub) and not get into it and see if that clay turns black too, or stays the same color. We'll let you know the results.