What makes a coat-dress foundation slip different from the other foundation slips (plain and tunic-dress) is the creation of sections of the slip using the dress material that can be viewed purposefully or inadvertently. The coat-dress foundation slip (illustrated below) is created for use with a coat dress that opens at the side front. By using dress fabric in a band at the bottom and up the side opening, it ensures that the skirt, when swinging open, does not show a contrasting material. Likewise, a vestee of the dress material is attached at the neckline so that it reveals the same fabric at the neckline.
When sewing a coat-dress foundation slip, start with the plain foundation slip (the small figure on the right). Outline the sections for the dress material on the plain slip pattern and then trace to other paper to create a pattern. The lower band replaces the slip lower section so seam allowances need to be added. But the vestee forms an additional layer on the foundation slip, attaching with snaps.
The coat-dress foundation slip can have a round neckline, a square neckline, even a camisole neckline, as needed. As always, adjust the slip to fit the requirements of the coat-dress.