What does it mean to lock stitches?
A lock stitch is actually a very fundamental stitch on any sewing machine – when the machine makes single stitches, the top and bottom threads “lock” together, keeping them secure in the fabric. If you can sew a straight stitch on your sewing machine then you are probably already sewing a lock stitch.
What is the difference between chain stitch and lock stitch?
Chain stitch strength is higher than the lock stitch. Lock stitch strength is lower than the chain stitch. At the top of the stitch, it appears like a lock stitch and at the bottom, it looks like a double chain. On both sides of the stitch, it appears the same.