Howdy Rory,
I have a question regarding hand-sewing long, straight seams (Example: the centerback).
Is there a preferred method to keeping an even tension / straight finished seam when sewing by hand? Which stitch would be best: half-back?
I ask, as I do not have access to a sewing machine when I travel, but might like to work on a coat anyhow.
Many thanks. Take care!
I look forward to Rory's response, but here's what I observed: My teacher always worked on a flat surface. The seam line was first chalked on the wool with a ruler. He would start by basting in the seam allowance next to the sewing line. He used basting thread, which is made to break easily and be easily removed when the work is done. (Basting may be less necessary for professionals working a straight seam, but it was helpful for students.) He started with a large, visible basting knot, although some people prefer a couple of stitches taken on top of each other or some backstitches. He would use a longer needle than he used for permanent stitching and control the fabric with his fingers, although students could pin if they wanted to.
Many wools are "grippy" and he would take advantage of that quality to keep the pieces together. He would take a couple of larger (3/8" to 1/2"?) stitches at a time and then would carefully pull the thread through, flattening the stitches. He would gently place his index finger on the hole from which the thread was pulled to control it. He would finish the line of basting with some backstitches.
As for keeping the stitches straight, some people will use the thread a guide. They pull out a little in a straight line and then follow it. With the stitching line marked by chalk that's not necessary.
With the seam basted, it was easy to control for the permanent stitching. He would use a shorter, finer needle. I've never seen a major seam sewn in a tailored garment with anything other than a backstitch and usually it was done by machine. The center back seam has to be strong. Another place that sometimes is hand stitched is the crotch. It's obvious why that would have to be strong. It's important not to place too much tension on the thread when sewing. One tailoring book I read described it as laying the stitch in. It helps to stand or sit on a stool in a relaxed, comfortable position with plenty of time to finish the work.
As I don't sew that often, I usually spend a little time sewing some practice stitches on a sample of the wool I'll be using before turning to a garment.