Yes, but only for very thin, light or decorative leather that won’t be under much stress. For most leather projects, regular thread tends to snap, wear through or rot. A heavier polyester or nylon thread is the safer choice.
When regular thread can work
“Regular thread” usually means standard all-purpose sewing thread. Two things matter most: the fibre and the thickness. All-purpose polyester is a reasonable choice for thin, soft garment leather such as lambskin, and for very light decorative work. 100% cotton is a poor choice for leather at any weight.
Regular thread can be acceptable for pieces that won’t be pulled, bent or flexed much, such as a thin leather patch or a light craft piece.
Why regular thread usually fails
- Snapping: standard all-purpose thread is thin. Under the tension of thick leather, or when the finished item is pulled or bent, it can break.
- Cotton rot: 100% cotton thread rots with moisture and sweat, and the tannins in leather can speed that up. Cotton also wears through at the edges.
- Poor fit in the holes: regular thread is too thin to sit well in stitch holes. It can look lost, or cut into the leather if pulled tight.
- Late failure: abrasion and tanning chemicals weaken poor thread slowly. Failures often show up months after the project is finished.
Thread sizes compared
Thread thickness is often given as Tex, which is the weight in grams of 1,000 metres of thread. A higher Tex number means a thicker thread.
| Thread | Approx. Tex | Notes |
|---|---|---|
| All-purpose polyester | About 27 to 30 | Fine for thin, lightweight leather |
| Upholstery thread | Around 70 | A middle ground for light bags and small goods |
| Bonded nylon #69, #92, #138, #207, #277 | 70, 90, 135, 210, 270 | Bonding stops the strands from fraying at the needle; usually used on industrial machines |
Bonded nylon sizes are not the same as all-purpose sizes, so check the Tex value on the label before comparing.
Threads that work better
- Polyester: doesn’t rot from leather tannins and has high tensile strength. It resists UV better than nylon, so it’s the better choice for items used outdoors.
- Nylon: strong, but sunlight degrades it faster than polyester does.
- Bonded nylon or bonded polyester: the usual choice for machine sewing of bags and belts. The bonding keeps the strands from separating at the needle.
- Waxed polyester or waxed linen: for hand sewing with a saddle stitch. The wax adds grip, helps the thread slide through the holes and resists fraying. See how to hand sew leather for hole spacing and technique.
Hand sewing and machine sewing thread
For hand sewing, use waxed braided polyester or waxed linen about 0.45 to 0.8 mm thick. If your thread is unwaxed, you can hand-wax it with beeswax.
On a home machine, a polyester in the Tex 30 to 40 range is the usual choice for thin leather. Heavier thread, such as bonded nylon at Tex 70 and up, is generally for industrial machines. Check your machine’s manual before trying heavier thread. For more on machine settings, see can you sew leather with a sewing machine.
Substitutes that don’t work
- Doubled regular thread: two loose strands abrade and tension unevenly. Doubling it doesn’t make it leather thread.
- Waxed cotton: it’s still cotton, so it can rot.
- Embroidery floss: it’s weak for leather work.
- Monofilament fishing line: it can cut into leather and loosen knots.
Test before you commit to a project
- Sew a scrap of the same leather with the thread you plan to use. Pull the seam firmly to see how it holds.
- Check the label for the fibre (polyester or nylon) and the size (Tex or bonded size).
- Remember that a quick pull test can’t show how a seam will hold up over months of use.