I have used a piece of flannel in place of batting when I didn't want much thickness and it works great. Just be sure to pre wash the flannel to ward off any further shrinkage.

That’s all you need. It will be easier to wash and dry without batting.

I make a lot of blankets for Project Linus and for gifts where I piece the front with blocks that include embroidery designs and I use flannel or fleece for the back. I make sure the flannel and fleece are washed before using. I than put the together using a simple stitch in the ditch method or tack them down using my button stitch on my machine. I always make binding that matches the fabric on the front and add the binding. It makes a nice lightweight blanket and it washes really well. Every mother that I have given them to love them and use them all the time.

I also make some for Project Linus with flannel backing--no batting. They are easy to do the quilting on. My understanding is they use the 30" ones for babies in a hospital setting.

Two of my bedrunners have been made and quilted without batting and well washed flannel backing. Easy to quilt. I use a long serpentine stitch down the seams up and down and side to side. Very pretty.

One is two tops, not flannel or fabric 'backing' fabric. Fabulous.

I have made several for ourselves (live in Phoenix). I still put in a very thin batting for a baby quilt. It just looks nicer in my opinion.

I often do that with baby quilts (we are in So California not the frozen North!). Also, my youngest used to make lap quilts for her friends to take to competitions and games and she used a thin flannel instead of batting so they could be rolled up and carried in their backpacks. They were perfect.

I just finished a flannel string quilt and put flannel on the the back and quilted it just fine, now batting and it turned out very nice.

I made both my boy's a quilt each with top and flannel backing only. One is 48 yrs. old and one is 46 yrs. old. I still have the 46 yr. old one that the grand's have used. Couldn't tell you how many times it has been washed over time. It still is in great shape.

Question
 

I'm looking forward to doing a flannel string quilt also. Did you use regular quarter inch seams and what did you use for the foundation. Thank you!!