Quilt Back Preparation
Quilt backing (and batting) should be at least 6” longer and wider than your quilt top (3” bigger all the way around). This extra fabric is a must to be able to attach the quilt to the bars of the frame.
If you piece your backing make sure to trim the selvages off as they shrink unevenly when you wash the quilt and create a puckered line. Use a ½” seam allowance and press the seam open. Square up your quilt back. You can do this by folding it in quarters and using your rotary cutter and ruler to trim it even. Again, make sure your back is at least 6” longer and wider than the quilt top.
If you choose a directional fabric for your backing fabric take that into account when piecing. Lastly, please mark the top of the backing fabric.