Water soluble thread would not work for washing the quilt top. After posting so much, though, it occurred to me that you might be able to avoid washing the top simply by airing it out for a few days - out of sunlight, though, to avoid fading. Fresh air might be enough to make it tolerable for quilting. Also, you could try putting it inside a plastic bag for a week or two along with several pairs of Dr. scholl's odoreaters shoe inserts with charcoal. The charcoal absorbs odors. These would be much safer options to washing - not to mention less work!

Thanks, Prism. I am on my way to working out this problem. Actually, sewing it onto a larger piece of muslin did come into my thoughts last night. Your ideas will work, I am sure. Can't wait to get started on it. I'll keep y'all posted on how it is coming along.

Could you spray it with a fabreeze type spray? I think they have a liquid spray. I bought an off brand at the dollar store one time when traveling. It worked for what I needed it for. Since you are at home, you could spray then air it out outside or on a porch?

I would not press it if you want to work on a color bleeding. (re ans. #6).