If you are a denim purist, you will probably be looking for one or two things, when you turn up the cuff on a pair of jeans. Do the jeans have selvage? Is the inseam felled? And quite importantly are the jeans hemmed with a chain stitch? Today we will be talking about the subject of chain stitching.
As I said, if you are a denim purist, you will probably be looking for the chain stitched hem. Preferably done by an old Union Special machine, such as the 43200G. In reality this doesn't serve any functional purpose. I would actually dare saying that a regular lock stitch would hold slightly better, but a good chain stitch has the potential to create what is commonly known (among denimheads) as roping. Roping is caused by the opposite pull of the denim. And one must not forget that chain stitching and potentially roping is an original feature or detail of vintage denim.
The old Union Special machines were used on the old Levi's factories, but back in the days the workers dreaded the chain stitching machines - and they probably still do. They weren't easy to operate or maintain, according to many sources, and you couldn't back stitch on it, which is why you will often see the chain stitch crossing over itself. They were used because it was practical sewing with the chain stitch, as it is a loop stitch and therefore you can sew a long continous stitch without taking the limitations of a small bobbin into consideration.