Are your quilt blocks always too small? This is very common for the self-taught quilter. We know each piece has a cut size and a finished size. The cut size is a half-inch bigger than the finished size. We sew a scant quarter-inch seam allowance on both sides of each piece, causing the finished (seam-to-seam) size to be a half-inch smaller. Sounds easy… so why do our blocks turn out too small?
The key word in the last paragraph is scant. A quilter’s seam allowance must be less than a full quarter-inch to allow for the thickness of the fabric. Think about creasing a piece of paper in half. Paper has almost no thickness, so each half is exactly half the measure of the full piece. Now think about a thick piece of cardboard folded in half. Because the cardboard has body and thickness, the two halves don’t exactly add up to the measure of the whole piece.
Fabric has body and thickness. When you sew and press a seam, you are creating a crease along the thread line. A tiny measure of fabric is lost within this folded space. We must plan for this loss by undersizing our seam. When you sew, adjust your needle to be closer to the raw fabric edge by one or two thread-widths. Do a practice seam to determine the exact amount of adjustment needed. To test your practice seam, measure the finished, pressed piece from seam to seam. Sew much happier!
Information provided by Kelly Irwin, owner, Quilting Connection, 238 Main St. Ames, 515-233-3048.