Originally Posted by isewhappy
The top was not prewashed. Should I just wash the flannel once and then put them together?
You can still use flannel on the back, but you will want to wash and dry the flannel first. Twice. Flannel can shrink at an astonishing rate, even on the second go-around.
Are you planning to quilt rather than tie? Quilting helps keep fabrics from shrinking excessively. The quilting ties the fabrics to the batting, so that the most the fabric can shrink is how much the batting shrinks. The heavier the quilting, the less difference there is in fabric shrinkage among the fabrics used.