How To Choose The Best Thread For Finer Leather Work

Recently a Reddit user asked what is the best thread to use for fine work. Many people wrote in to say that our thread was at the top of their list.

Reddit -Best thread for fine work

If you’re looking to improve your work, here are some thread- related tips to help:

Stitching consistency is the most important thing

No matter what thread you choose, sewing consistently uniform stitches will make your work look ‘finer.’ The thread can be beautiful, but if the stitches are all over the place that will be the first thing people notice. I did a post a while back on saddle stitching and every person had an almost mechanical replication of their sewing movements. They didn’t squirm to see if their awl was going in correctly or peeking back and forth from one side to the other. Consistency of movement will transfer to your stitching.

The back side of the stitch is a gotcha for most beginners. One of my teachers described it as the ‘beginner’s mountain range’, because the haphazard stitch pattern looked like a panorama of the Alps. As you get better, your awl will go into the stitch mark exactly perpendicular to the surface. When sewing, you can isolate both axes where rotation happens: front to back where the stitches look smaller or larger, and top to bottom where the stitches go either closer to or further from the edge. Front to back rotation typically happens when you flick your wrist going into the stitch. When you do that, the tip of the awl follows an arc path in the right to left motion. The top bottom rotation usually comes from raising or lowering your elbow.

If you’re looking to improve your stitching technique, try holding a big wooden spoon and, without thinking about it, make the same movement as you do when you use your awl. Hold the spoon part like the flat of your awl. The longer handle will exaggerate the movement and you’ll be able to see where you tend to drift.

Match stitching to the thickness of thread

By the numbers, here are the thicknesses of our thread:

332 – 0.77mm thread diameter

432 – 0.63mm thread diameter

532 – 0.57mm thread diameter

632 – 0.51mm thread diameter

832 – 0.43mm thread diameter

We have a chart that shows our different thread thicknesses in the same 9tpi stitch count. 0.1mm doesn’t seem like a lot, but you can see the difference in thickness, especially side by side.

I recommend 532 or 632 thread at 9tpi if you’re going to use just one size of pricking iron and thread. The 9tpi is an all-around good size for both bags and accessories. This is what I use the majority of the time and it works great for finer work.

If you’re going to 7tpi, I recommend the thicker 332. The smaller threads don’t look great at low stitch counts and won’t hold the seam as long. The 332 looks good for larger work like handbags and duffels. Again, you can use 9tpi and 632 for larger work, but some styles match better with the thicker look.

If you’re going to use 6tpi or larger, I’d actually recommend a different line of thread that has thicker sizes. I don’t see the larger sizes used much in luxury/fine work, though they are often used in more rugged styles.

If you’re doing very fine work like watch straps, I’d recommend 832 at 10 or 11 tpi. This gives a more delicate feel to the work and the thread looks more appropriate to the size of the project.

Recently I did a tear-down of a luxury bag and saw that there were two thread thicknesses being used on different parts. They used the equivalent of 332 for the straps and handles at 7tpi, and 632 at 9 tpi for the rest. The size difference seemed to be more for aesthetics since both would hold up equally well.

Small details make finer work

Making finer work is all about the details. There are often many small differences that separate the very best work from its competitors. Our thread is re-twisted to make it a little bit denser than others. You would think that the difference would be minor but, as others have confirmed, it really makes the thread stand out.

Similarly, you can do a number of things to make the thread-related details of your work better. Below are a few that you can try individually or all together.

Contrasting stitch. Use a lighter color thread on a darker leather or vice versa to really highlight your stitching work. It is also a way of challenging yourself to improve your sewing because it will really stand out.

Match color to lining or edging. If you match the exterior thread to the interior of the bag, it can really make the colors “pop” when the bag is opened. A good example of this technique is to use red thread on the outside of a gray bag to highlight a red interior.

Minimize the hole size. If you’re using a drill or lace marker, mark your stitches using a tool to make smaller holes like a pricking iron or pricking wheel. Minimizing the hole structurally makes the stitches stronger and gives it a nicer look.

Sew instead of riveting. Using rivets is a big time saver for creating belts or straps, but sewing them can create a finer look. Though it takes more time to sew a strap closed than it does to rivet it, the results are worth it.

14 replies on “How To Choose The Best Thread For Finer Leather Work

  • Josh

    Hi there. Your article references 9 tpi (teeth per inch), but the chart states 9 spi (stitches per inch). 9 spi = 8 tpi. So which is it?

    thanks!

    josh

    Reply
    • Fine Leatherworking

      Great catch! The stitches I used in the picture were made with a 9tpi iron so the picture caption should actually say TPI not SPI.

      Reply
  • Tommy

    Hi, I am an amateur leather worker and have heard that polyester thread is the strongest and best thread to use. Could you explain to me why this linen thread is so good? I am sure it is a matter of opinion but I would to hear both sides of the story 🙂 Thank you!

    Reply
  • Katie Siepierski

    Hello!
    I am fairly new to leather, and your site has been ao very helpful, thank you!

    I wanted to ask your advice if you wouldn’t mind. I have some ideas in my head and will be practising first of coursw, but before I start buying more supplies that I want to test out I really wanted to ask for your opinion.

    I want to make a vest for myself and my daughter- i will be using 1oz deerskin and some very well tanned, thin, but prime fur silver fox hides. My idea is to have the leather on the interior of the vest (not sure if i want leather side or suede side facing inward yet) and the silver fox pelts on the outside. The stitching will all be done by hand, and I am looking for consistency, quality, strength and durability. But, worat case scenario during wear, I would much rather the thread break than the leather tear at the seam like a perforated check.

    I was thinking of using the equivalent of size #69 thread and size 18 needle, but I am not sure how many SPI I should have. I was thinking maybe 7 SPI?

    But then I worry maybe I am thinking about this too delicately? Or overthinking it.

    If you were hand sewing a vest with 1oz deerskin and fine silver fox pelts, what would you use for thread, needles, and for marking the stitches? Any input would be greatly appreciated, thank you for your time

    Reply
    • Fine Leather

      Hi Katie – feel free to send us an email and we can help you out with the details. Email details are on our page at fineleatherworking.com. Thanks!

      Reply
  • Mark Main

    This is a great site, thank you for doing this. I was looking for a TPI / SPI formula (or chart) for the French pricking irons, which is what led me here. If you have a chance to post something on this it would be appreciated. Also, anything that helps with deciding on the best TPI for large vs. small bags, vs. wallets and belts. Thanks again!

    Reply

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