What is a ladder stitch?

A ladder stitch closes a seam from the outside without any stitching showing. It is the stitch for the gap you left to turn something through — cushions, soft toys, lined bags, the hem of a lining.

How it works. Fold both raw edges in along the seam line and press them. Bring the needle out through one folded edge. Take a small stitch — 3 to 5 mm — inside the fold on the opposite side, entering directly across from where you came out. Then cross back and do the same on the first side. The thread makes a ladder between the two folds. Every 4 or 5 rungs, pull the thread gently and the ladder disappears into the seam.

What makes it invisible.

Press the folds first. The stitch follows the crease. Without a pressed crease it wanders and the seam looks lumpy.

Enter directly opposite where you exited. Stepping forward on the crossing is what produces a visibly gathered join.

Keep the stitches short and even. Long stitches leave gaps that open under strain.

Use a matching thread and a fine sharp needle.

Knot at both ends — a slip knot buried in the seam at the start, and a couple of tiny backstitches inside the fold at the finish, then bring the thread out a little away and cut it so the tail vanishes inside.

It is also called a slip stitch, invisible stitch or mattress stitch. The names vary; the movement is the same.