I have washed antique quilts in sodium perborate (used to be called all fabric bleach). You do need to soak them a long time, changing the solution several times (days). Usually had good results. One quilt I did for a client was so bad, my DH thought I had ruined it when he saw the "after". It had looked like beige fabric when it was really off-white.
If it is just a top, do it in a tub and lay flat somewhere to dry. Do not wash in a washer or dryer, it will unravel badly.