Not so much a product as a process.
1.Use very, very hot water, and plenty of it.
2.Add Synthrapol.
3.Soak the fabric at least 12 hours.
For very detailed info on how this works and pictures of examples, see Vicki Welsh's blog about hand-dyeing her own fabrics and how she SETS THE DYES PERMANENTLY here:
http://vickiwelsh.typepad.com/field_...ness-post.html