Rewash the quilt by itself as quickly as possible. Sometimes if you rewash fabric with a color stain immediately after the stain occurs, a portion of the stain will wash out and it will become easier to completely remove. Do not dry the quilt.
Pretreat the color stain with heavy-duty liquid detergent. Let detergent soak into the color stain and then apply another coat. Pretreat for at least ten minutes and then rinse the quilt.
Soak the quilt in diluted all-fabric powder bleach for several hours.
Launder the quilt again to remove the all-fabric bleach.
Use a commercial color-remover if the stain persists. Only apply color-remover to the color stains; otherwise, it can strip all of the color from your quilt.