That are my 18th century black wool jumps. Jumps (less boned, unboned, or quilted) were an alternative to boned stays in the 18th century. They could be worn during work or pregnancy, or at home (‘déshabillé’).
For my jumps, I’ve used a small leftover piece of black wool or wool blend fabric which I’ve had in my stash. It’s machine-sewn with hand-sewn eyelets. And it closes in front with spiral lacing. In this painting, the maid is wearing black jumps which close in front with spiral lacing.