I used Cream of Tartar to remove rust. Wet area, sprinkle it on thick and cover spot to keep it wet. It took several hours, but the rust came out. I know how you feel about the ruined quilt. I stored two quilts( very old!!) in a metal trunk in my basement , then a couple years later, the basement flooded and while cleaning things, opened the trunk to a black, wet mess. My husband told the cleaners to toss whatever it was, and after it was too late to examine them, it dawned on me that it was my antique quilts. One quilt my great grandmother had made and it was in poor shape, the other was from a country homecoming picnic.. It was embroidered with names that people paid to have added. Family names were in a wheel and spoke pattern, attached to a large wheel and spoke. All the names were written in script, and really small size. Since it was from a town that was founded by my ggg- grandfather, I planned to take it to the county historical museum for display. I had wrapped those quilts in pillowcases so they wouldn't get harmed, and I'm still not sure why they had all the black mold on them, but you can believe I did a lot of crying and beating myself up.