Originally Posted by
HouseDragon
Since I started adding the Dawn about a month ago, I've been shocked to see the new catcher comes out white: Dawn stops the bleeding dead in its tracks! 
Actually, the Dawn does not stop the bleeding but acts more like Synthrapol in that it suspends loose dye particles in the water so they do not settle on your color catcher. If you have a bleeder and you want to set the dye you must use a dye fixative like retayne.
Dawn is great to use if you inadvertently used a bleeder in a completed quilt. It has been known to not only remove the offending bleed but keep it from settling on neighboring fabrics again. A few months back I posted a link to a hand dying blogger who did a great experiment with testing dawn, synthrapol, Dharma's generic Synthrapol and another product with great results from blue dawn.
Here it is again
http://vickiwelsh.typepad.com/field_...read-this.html