Harness Needle

Harness needles are stout, blunt-tipped needles designed for hand-sewing leather that's already had its stitch holes made — with an awl, a pricking iron, or a stitching chisel. Because the holes already exist, the needle doesn't need to cut or pierce anything; it just needs to pass thread through smoothly, which is why the tip is rounded rather than sharp. A sharp needle used on pre-punched holes tends to split the thread of the previous stitch as it passes back through, weakening the seam.

Traditional saddle stitching uses two harness needles at once, one on each end of a single length of waxed thread, passed through the same hole from opposite sides so each stitch locks itself in place.

Sizing

Harness needles are sold by number, and confusingly the numbering isn't perfectly consistent between suppliers — always check the actual diameter against your thread rather than relying on the number alone. As a rule of thumb, the needle's diameter should be close to the thread's diameter: too thin and the needle won't open the hole enough for the thread to follow smoothly, too thick and it will distort or tear a hole sized for a finer thread.

How to use it

1. Thread both needles onto opposite ends of a single length of waxed linen or polyester thread.
2. Pass one needle through the first hole from front to back, pulling roughly half the thread through so both sides are even.
3. Pass the second needle through the same hole from back to front, taking care not to pierce or split the first pass of thread.
4. Pull both threads snug and repeat down the seam, alternating needles through each hole.

Care

Harness needles don't need sharpening since they're meant to stay blunt. Store them somewhere dry, since fine steel needles can rust, and keep them away from where they might bend — a bent needle tracks poorly through a hole and is difficult to straighten reliably.