My parents visited Brimfield, Massachusetts, back in September for the massive antique fair that takes place there 3 times yearly. Luckily for me, their trip to Brimfield happened to be en route to my house! I say luckily for me, because my mom brought goodies!!
One of the treasures she arrived with was a stack of vintage quilt blocks - some finished, and some not quite. I can't wait to get down to finishing them, and creating whatever sized blanket they may cover. From what I have read about using vintage quilt blocks, you are better to wash them as a whole when they are already completed in a quilt. The strength of the backing material (which should not be vintage, as the vintage blocks need the support of new fabric), and finishing, will help to keep them together. I suppose though, that it may be worth knowing, before you venture to spend the time on quilting them, if they will completely fall apart!
Just look in the last photo at the hand stitching. This is a pretty big pile of pieced quilt blocks. That makes for an incredible amount of time spent stitching by hand. Just amazing...