If there are outside corners inside the house, there has to be a way to finish that corner so it is straight, plumb, and smooth. Today, metal corner beads are used with joint compound applied to smooth the transition between the side of the bead and the sheetrock. Colonial plasterers did not have corner beads to apply to the outside corners. Instead they attached wood beaded corner boards at the corner and applied the wall plaster up to the board. The corner board provided the smooth edge at the corner. All the outside corners inside our house have wood beaded corner boards.