Originally Posted by LDB
Becky at my LQS (Sunshine Stitches) explained it to me this way:
Use Retayne to prevent fabric from bleeding. Use Synthrapol (or other fabric catchers when your fabric has already bled. If you think a fabric might bleed, prevent it by using Retayne. If you have a 'surprise' of bleeding, Synthrapol will help remove the runs.
She always knows how to break down a matter for a dumb newbie!
This is not really accurate.
Retayne should not be used on any completed quilt, only on fabric before it is combined with any others. You only need to treat with Retayne once, but the quilt made with treated fabric should be washed in warm water with a cold rinse in order to preserve the “lock” on the dyes. Do not wash the quilt in hot water.
Synthrapol will keep floating dye from setting in the wash, but it will not remove dye that has previously run and set (in the dryer for instance), so it will not 'fix' any oopsies of the past. It is the same as a Color Catcher. You add Synthrapol to each wash as long as your fabric keeps bleeding.
Simply put, use Retayne before you sew things together, not after. Use Synthrapol after you sew things together.