This section is from the book "A Treatise On Architecture And Building Construction Vol3: Stair Building, Ornamental Ironwork, Roofing, Sheet-Metal Work, Electric-Light Wiring And Bellwork", by The Colliery Engineer Co.. Also available from Amazon: A Treatise On Architecture And Building Construction.
In Fig. 29 are shown an elevation and section of an open stringer, where fillets are used. At (a) is a portion of the stringer showing the step trim with fillets a, a; the lower portion of the stringer is relieved to form a facia b, and the edge is formed into a quirk bead, against which the plaster would finish. This method, although often used, does not give as good a bond for the plaster as does the soffit mold shown at A in Fig. 28, in which the edge of the stringer is kept square. At (b), Fig. 29, is represented a section of the fillet, mitering with the riser, which shows that the face stringer requires to be kept back the thickness of the fillet, in order that the latter may miter properly with the riser.