I felt bad. The damage was done. There was very little I could do to help. A friend of mine washed the quilt top before she brought it to me to be quilted. The quilt top was all mis-shaped, bunched, wrinkled and knotted on the back. Through her tears she said, "But it smelled really bad! I couldn't bring it to you to quilt when it smelled so bad."
Please do not wash a quilt top before it is quilted. No matter how badly it smells. I have seen this many times and it is never good! Sometimes the quilt top can be saved but, in my opinion, it is not worth the risk. More often than not, permanent damage is done to the quilt top.
Washing the quilt top before it is quilted and bound can cause alot of damage. Especially if you wash it in your washing machine. The edges can unravel, seams can unravel and even come open, the unraveling will cause bunches of knots on the back. The fabric in the quilt top can pull and be left puckered, pulled out of shape, wrinkled or dimpled.
I know quilt tops are sometimes stored in basements, garages, attics, under beds and in the backs of closets. I have even heard of them being stored in a barn or two. I have seen them stored (hidden) in trunks of cars! I also know that sometimes quilt tops are found in estate sales, garage sales, and flee markets. Some of them smell really bad. Musty, moldy, damp, like moth balls or worse --- but, no matter what the smell, do not wash the quilt top before it is quilted.
Believe me. If you bring a smelly quilt to a long arm quilter, it will not be the first or the last smelly quilt she/he sees (or smells).
If, however, you absolutely cannot get past the smell, there are a few things you can try.....You can hang the quilt top outside for a few hours and let nauture take its course. (Do not hang the quilt top in direct sunlight if you are worried about fading.) .....You could spray the quilt top with a product like Febreeze. .....If you have a fabric steamer, you could also try steaming the quilt top.
Please do not spray the quilt top with perfume or a deodorizer. These products just mask the smell for a while then you smell a perfumey bad smell.
Once the quilt is quilted and the binding is attached you can wash the quilt successfully and enjoy it for years to come.