Thanks everyone, I quilted mine on my longarm, not my sewing machine.
You don't actually need a foundation to do string quilts, they work just fine without it.
I very often use flannel sheets from LLBean for quilt backs. They're really nice, are sold separately (instead of buying a sheet set), and wash and wear on quilts beautifully. This is the back with the sheet I used:
I always prewash and dry the flannel sheets, hot water hot dryer. I don't prewash my quilt fabrics. When I'm finished, I wash the completed quilt, the prewashed flannel and the unwashed top come out just right.
I used Quilters Dream cotton, select weight.
Created by CJ