If you are sewing lightweight leather, use a leather needle or glovers needle. These have triangular points which cut through the leather. If you are sewing heavyweight leather you will need an awl or bradawl to pre-punch holes in the leather and then use saddlers', sailmakers', or tapestry needles to sew the leather. You will need to use strong thread when sewing leather. Strong cotton may be adequate for thin leather, but waxed thread is recommended for thicker leather (especially when making shoes).
The strongest stitch for leather is saddle stitching (sometimes called cobbler’s stitch). Two needles are used at once, each making a row of running stitches. They are pushed through the leather alternatively so that one thread pierces the other, thereby locking the stitches and preventing 'running'.
For shoe making you will need to know a few variations on running stitch and saddle stitch. The stitches are basically the same, but the needle is not taken directly through the leather.
Edge-flesh/edge-grain stitching is used to attach the soles to the uppers. The needle is taken through the flesh side of the sole leather, but instead of carrying straight through, it comes out of the side of the sole. The needle then continues straight through the upper from grain side to flesh side.
This stitch can also be done with two needles as a saddle stitch.
Edge-flesh butt seams
Edge-flesh butt seams are used to attach edges to shoes and for the main seam of the upper – and are also used for the leather covering on a scabbard. The needle goes from the flesh side out of one piece of leather then through the edge of the other piece to the flesh side again. This stitch can be worked as running stitch or saddle stitch, but it is usually done as a saddle stitch for extra strength.
Shoes from York and Heddeby had a single thread whipped around the leather edge that forms the opening of the shoe. Presumably the leather would be reinforced by this technique and also the idea can be extended to reinforce the mouths of pouches. An example of this reinforcement method appears amongst the textiles from Saxon London. Here, two contrasting colours were sewn alternatively along the edge providing a decorative effect. Like the London example, some of the York shoes used a brightly contrasting coloured thread along the edge, the result being decorative as well as functional.
The technique is applied with a single glovers needle, waxed linen thread, and an awl. Pierce a row of holes around the mouth of the shoe or pouch etc. about 1\8" - 2mm. apart and the distance below the edge of the leather. Start by sewing the thread around the first two holes, three or four times, then run the thread through one side, over the top, and back through the next hole on the same side. Finish the seam off in the same way as at the start.