What Does It Mean to Do an Understitch in Sewing?

Purpose

• The understitch is used to keep the interior fabric piece from appearing behind the edge of a garment. The technique works to keep the seamed fabrics flat and in place, preventing interior fabric from rolling up or folding over a seam and becoming apparent from the outside of the garment.

Application

• The edge seams of a project with an interior lining or facing can benefit from an understitch. For this reason, application of the understitch is common at necklines and zippers, but it can also be applied to any straight or curved garment edges, including arm holes, cuffs and pockets.

Process

• The technique is applied to a project after the edge seam between an outer and an inner fabric has been sewn, trimmed and ironed flat. The understitch is commonly sewn by sewing machine, but it can also be accomplished by hand, using a pick stitch. The understitching follows the line of the edge seam and can be ended short of difficult corners.

Result

• The result of the understitch is simply a straight line of stitches, typically 1/8 inch from an edge seam. It is apparent only on the inside of the garment, as it is sewn only through the interior fabric and the turned excess left by the seam with the outer fabric. This extra line of sewing finishes the seam and keeps the interior fabric inside of the garment.