Plastering - External angles

In early lime plastering it was common to find external angles (e.g. on a chimney breast) formed in a harder plaster or protected with long timber strips. Nowadays, galvanised or stainless steel angle beads are the norm, and these are fixed with nails or plaster dabs prior to plastering, as shown in the left-hand photograph below. Galvanised beads can be damaged by the razor-sharp edge of the trowel. As the galvanised surface is scraped away, the bead is free to rust and, in the humid conditions which can occur in the drying-out process, decay can be rapid. Angle beads are available for plasterboard (see the right-hand photograph below).