Waxed threads for leather
For sewing leather, waxed threads of various thicknesses are usually used. You can also use various threads for sewing machines if you pre-wire them (just pull the thread through a piece of beeswax several times, and then through a rag to remove any remaining wax). Waxing prevents the thread from unraveling and passing through the hole more smoothly during the sewing process.
Waxed threads come in different types, the main ones being polyester and linen (including ramie). Which of them to sew is the preference of each master, or the choice is made for a specific product. Linen threads do not stretch during work, but are more susceptible to unraveling (they need to be tucked more often) and it is more difficult to close the tip at the last stitch, unlike polyester threads.
By the type, waxed threads for leather are divided into round and flat. Round threads can be twisted from several fibers or braided, where the rest are woven around the central fiber - such threads are more expensive, but in their characteristics they are close to linen, having all the advantages of polyester. Flat threads are all braided and, as a rule, their thickness is at least 0.6 mm.