I finally made up my mind and ripped the binding off a too-narrow quilt. Since I do QAYG it is no problem to add another border.

The original quilt has been washed a couple of times. How much extra should I add to new border to adjust for shrinkage?

I will make the borders x" longer, sandwich, quilt, and wash them. I intend to baste scrap fabric over the raw edges for washing.

Cotton, and cotton batting. How much would you add?

Thanks