A four-step buttonhole is a function on a sewing machine that allows a buttonhole to be created in several successive steps. Unlike a fully automatic program, the machine operator manually switches between the individual sewing phases. Most commonly, it is a four-step process. In the first step, one side of the buttonhole is sewn. Then, the user turns the program selector to switch to the second step and sews the upper transverse reinforcement, known as the “bar-tack.” Subsequently, they switch to the third step to sew the second, opposite side, and finally to the fourth step to create the bottom bar-tack. This method of sewing buttonholes is typical for mechanical and simpler electronic sewing machines.
