I discovered a very old quilt that was so dirty that, while I feared it might disintegrate, it needed laundering. I prepared my washer just as though I was going to do a load and then put the quilt into the soapy water by hand and pushed it down repeatedly to get it clean, let it soak. When I thought it had been long enough, I put it through the spin cycle, filled with rinse water and repeated the hand "agitation" as though it had been in the sink or tub and again through the spin. I can never get enough water out of things doing them only by hand and this way the piece was not being wrung out. Put an old sheet on the lawn and spread the flimsy on that to dry. This will help keep the shape and lessen the stress on the unstable quilt. If it is musty smelling, put some vinegar in the wash water. See how it comes out before you toss it. Somebody used a lot of time and love creating this and the person who donated is hoping someone can make use of it.