The Three Saddle Stitches

The Key

Saddle stitch isn’t one stitch, but a family of three. Seeing, naming, and understanding the different ways two running stitches can alternate through one line of holes informs choices at every stage of leatherwork: design, modification, and repair.

This page names, describes, and shows each saddle stitch in words, pictures, and three-dimensional models. Then it covers some techniques for achieving them.

Takeaways

1. For the flattest looking stitches, alternate right-over-left and left-over-right. For slanted stitches, use either right-over-left or left-over-right consistently.

2. When stitching toward the body into diamond holes slanted down-and-toward to up-and-away, stitch right-over-left to steepen the slant of stitches on the right side and left-over-right to steepen the slant of stitches on the left side.

3. Feel free to use needle placement in the hole, casting, or both to set stitch direction, but avoid placing a needle high and then casting over it. That ties a knot.

Stitches

Two simple stitches alternating in one set of holes can run three ways: parallel, Z-twisted, or S-twisted. This section shows and describes each way, then compares them in a table.

Parallel

Looking at a parallel saddle stitch from above, as we might look down at a project clamped in a stitching pony, the threads crisscross side to side. Imagine we took a knife and cut off the top edge of the leather, so we could see down into the holes:

However, looking at the same stitch from the side, parallel saddle stitch threads don’t also crisscross up and down. One thread always lies above the other.

Notice how flat the stitches lie. Each stitch runs either from the top of its starting hole to the top of its ending hole or from the bottom of its starting hole to the bottom of its ending hole.

The threads aren’t twisted, just staggered. They run in parallel.

Z-Twisted

Looking at a Z-twisted saddle stitch from above, reading top-to-bottom, threads take turns crossing over each other from right to left, like a corkscrew, the threads of a bolt, or the stripes of a barber’s pole:

Looking at the stitch from the side, we see the opposite of flat, parallel stitches:

It doesn’t get more slanted than this. Each stitch runs directly from the bottom of the previous hole to the top of the next, making steep diagonal lines described as “zigzag” or “falling dominoes”, à la Hermès.

Stitches on the left side are also slanted, but less steeply than on the right. In practice, they may appear completely flat, depending on hole size, thread size, spacing, and other factors.

Z-twisted saddle stitches crisscross from the top and the side, not just the top, like parallel saddle stitch. In this sense, Z-twisted saddle stitches are twisted, and in a particular direction.

What about the other direction?

S-Twisted

Looking at S-twisted saddle stitch from above, reading top-to-bottom, threads take turns crossing over each other from left to right, like the stripes of a candy cane.

The right side of S-twisted saddle stitch looks like the left side of Z-twisted:

These longer stitches can also appear flat, rather than slanted, in person.

As for the left side, it looks like the right side of Z-twisted:

Here again are the prototypical, steeply slanted “dominoes”.

Reversing the direction of twist flips which side’s stitches slant more steeply.

Comparison

The following table assumes stitching toward the body into diamond holes angled down-and-towards to up-and-away.

Notice what’s not in the table: a perfectly symmetrical stitch. In diamond-shaped holes, one corner sits lower than the other, and two threads can’t occupy the same corner at the same time. If the stitch is twisted and the stitches slant, one side’s stitches slant more than the other’s. Even parallel saddle stitch has different threads on top, right and left.

Thread diameter, hole size, hole spacing, and other choices can also contribute to asymmetry. For example, piercing from just one side often leaves wider, crisper, concave entry holes and narrower, rounded, convex exit holes, especially when piercing as shallow as possible with an awl, saddlery style. Conversely, thread, holes, and spacing can also help stitches slant more steeply. Narrower threads in longer holes at steeper angles tend to do this.

In the end, the fundamental geometry of saddle stitches remains asymmetric. We can make choices to make the differences less noticeable, but can’t avoid them entirely.

Side Note on Twist

The world is full of helixes. You’re probably quite familiar with S- and Z-twists, though you may not have known these names for them.

Standard bolts and screws have Z-twisted threads. That’s why they advance when turned clockwise and back out when turned counterclockwise. “Righty-tighty, lefty-loosey” comes from being Z-twisted.

S-twisted threads are all around us, too, especially on things that normally spin counterclockwise. For example, we push the left-side pedals of bicycles counter-clockwise to go forward. We wouldn’t want pedaling to unscrew the pedal as we ride! So left pedals get “reverse”, S-twisted threads while right pedals get standard, Z-twisted threads. That way, pushing each pedal tends to tighten rather than loosen it.

More directly relevant to leatherwork, mills usually spin cords of linen and other fibers in Z-twists.

Since cords are Z-twisted, threads made of them are almost always S-twisted.

For example, Maine Thread’s pages for its twisted products mention S-twist by name.

Opposing twists make a thread more durable, since twisting forces that unwind the cords don’t also unwind their fibers.

Try unraveling a bit of twisted natural-fiber thread with your fingers. Then try unraveling one of its cords.

Techniques

To repair an existing stitch line, we need to know what kind of stitch it is in the first place. Only then can we choose a technique to match it. In new work, we can choose our stitch for effect: parallel for the flattest possible stitches, Z-twist for the steepest possible slant on one side, or S-twist for passable slanting front and back.

There are two key methods for achieving a chosen twist direction: placement in the hole and casting.

Placement in the Hole

If we want a particular thread to cross on top, we can position our second needle in either the low or high corner of the hole to put that thread on top.

This is the method Al and Ann Stohlman teach in The Art of Hand Sewing Leather. While they don’t discuss achieving different twists, they repeatedly emphasize placing the same way in the hole every time.

Again assuming stitching toward the body into diamond holes slanted down-and-towards to up-and-away:

• Put the needle from the right on top, get a Z-twist and steeper slant on the right.

• Put the needle from the left on top, get an S-twist and steeper slant on the left.

Crossing the second needle with the first to pull the first needle through speeds up stitching by keeping all our needles and tools in our hands. Practically, it also shifts the choice of twist forward in the stitching process.

It’s far easier to put the second needle through the far, high corner of the hole for S-twist by crossing it behind the first needle. We can reinforce this choice, and avoid piercing thread, by first pulling the thread already in the hole forward.

Conversely, it’s easier to put the second needle through the near, low corner of the hole for Z-twist by crossing it in front of the first needle. Again, we can reinforce this choice, and avoid piercing thread, by pushing the thread already in the hole back beforehand.

Casting

We can also change the direction of twist by positioning our first loop of thread, rather than our second needle.

This is the method Nigel Armitage teaches in his videos. Nigel always positions in the hole the same way: second needle above the thread in the hole. When he needs to twist the threads the other way, he casts the first loop of thread over the second needle.

Casting can override, or reverse, placement in the hole.

If we pause halfway through pushing the second needle through and cast the loop of thread around its point, so it hangs over the needle, pulling the needles to take out slack will cause the cast loop’s thread to ride up and over the other thread into the far, high corner of the hole. We positioned our threads in the hole for S-twist, but got Z-twist by casting.

Placement Versus Casting

On one hand, casting creates a pitfall. If we put the second needle through the near, low corner of the hole, but then also cast the loop over that needle, we’ve essentially double casted. Both needles end up routed through their opposite loops, so taking out slack reveals we’ve tied an overhand knot. There are good uses for this knotted stitch, but it comes as an unwelcome surprise when knots weren’t the plan.

One way to avoid knotting is always positioning the second needle high in the hole, as Nigel Armitage recommends. Positioning in the hole same say way every time requires casting to twist in the other direction.

Of course, another way to avoid knotting is never casting at all. Just use placement in the hole to set twist. That’s what The Art of Hand Sewing Leather recommends.

Both ways work.

On the other hand, casting is an easy way to tweak a familiar sequence of stitching steps to twist in the other direction. When casting, we don’t need to change how we cross the second needle with the first, how we tension the thread in the hole to avoid piercing, or how we place the second needle into the hole. We just need to add a cast. Or leave it out.

Some people may have no trouble teaching their hands two different stitching sequences, one for placing the second needle high and the other for placing it low. Others may prefer to reuse more muscle memory by doing everything the same but the cast.

Share Your Thoughts!

If you’re read this far, I hope it’s been useful to you. Please feel free to e-mail any thoughts to me at kyle@kemitchell.com.

I’d be particularly grateful for any resources or thoughts on an open question in my mind: Does casting offer any benefit in evening the slants of stitches on both sides beyond changing the direction of twist? Might it cause subtle changes to the shapes of the holes, like pulling the needles at angles to take up slack?