Setting Color

Barb · Posted: Sun Sep 16, 2007 8:17 am Post subject: Setting Color

We recently heard form a customer who had trouble with one of our denims. She reported that after numerous washes she was still finding dye in her washer and dryer. Of course, we were disappointed to hear this report.
I immediately took some of the fabric home and washed it three times. Clearly some of the dye came out in the first wash as one would expect with a dyded denim. The washed piece was brighter than the unwashed piece leading me to believe that some of the dye was removed making the color coverage less dense.
On the second wash I did not notice any difference and found no indication in my washer that any dye had come off, although I would not feel comfortable washing this with whites (!)
Finally after the third wash and dry, I dunked the fabric in a clear glass container filled with water. The water remained clear with the exception of some residual soap. No blue.
So here' my question: What makes the difference in experience. Our customer was careful in her prewashing, did everything "right" but had much worse results.
My theory is a difference in water. If all other factors are the same, it seems that minerals in different water supplies can be the culprit. Any thoughts on this?