I have worked with several vintage quilts. One is very scrappy and dirty, I long arm quilted, bind and washed it with orvus and put 3 pcs of color catchers. It turned all right. I am sure that the seams will fray and ruin the top if washed before quilting.
Another quilt was an heirloom appliqué, 28 dirty blocks, dismantled and individually hand washed, redesigned into smaller lap quilts which turned into beautiful treasures.