I went to visit a friend of mine today.
She started in the business as a machine operator (seamstress) at Samuelsohn; today she owns the company which makes their, and the majority of North American manufacturers’, canvas fronts.
She has special double-needle jumpstitch machines with custom-built forms. This machine doesn’t sew like most, whose presser foot and feed dogs feed the fabric- the operator feeds it through at their own pace. They can control how many stitches, whether lots for a firm shape, or few for a soft shape, and the forms allow them to work in the shape of the chest and shoulder. It requires a certain amount of skill since the operator is building in the shape and has to know how to do it correctly. They do a very nice job.
Canvas has not been though all the finishing processes like cloth has so there is still a big amount of shrinkage left. A tight canvas will make the fronts ripple, and I suspect this is one of the reasons some people put their canvases on the bias, since the bias allows more stretch. Whife alludes to it, and suggests that clever tailors are able to put the canvas on the straight grain without trouble. One of the most important steps to avoid trouble is to pre-soak the canvas fronts. They are soaked up to 24 hours, and then hung to dry, then pressed on custom-designed forms which retain and enhance the form of the chest, and stretch the shoulder at the same time. Some people then run some light shirring stitches through the canvas to draw it up a bit to prevent any further shrinkage problems.
those are interesting machines. a very reasonable hand stitching substitute IMO.
I'm following your blog for the same reasons I am sure everyone else does, an interest in traditional tailoring, and what goes on at the current time.
Speaking of canvasses, are there any options purely synthetic, washable, that would work for a travel jacket. Patagonia makes one, but they just line fabric with nylon taffeta. The travel jacket idea is to have garment that can be folded, but basically stuffed, that a touring cyclist, backpacker, climber, can pull out when they need to gain admission somewhere. Chounaird who created Patagonia is a world traveller and found the need. All the better today when non-climbing billionaires appear on magazine covers dressed in jeans and a jacket. But I was thinking just a little more structure than a Patagonia jacket, yet still reasonably trashable. Maybe just a lot of stitching in some kind of taslan,