My great Grandma's quilt that I redid was covered in brown spots. After seeing Retro Clean mentioned in a Quilt in a Day video I decided to give it a try.
The instructions say for best results soak outside in the sun for up to 2 days. I didn't do that. I soaked it in my bathtub for 24 hours. I didn't really know how much water was in the tub so I just guessed how much Retro Clean to dump in the tub.
Not every age spot is gone, but it is way improved. I'm delighted and will use Retro Clean again. If I can find a tub big enough I might even follow the directions!