The second method is the use of ‘L’-shaped corner blocks, which can be made from off-cuts of timber or bought as plastic versions in pairs. There is no fixed size for corner blocks but one block would be of sufficient size if it were cut from a block of wood of maximum size 75mm x 50mm x 50mm, or similar. Corner blocks are held in place by the tension of the line and have the distinct advantage of not damaging the mortar joints. However, they can only be used on external corners, and the use of pins is sometimes therefore unavoidable.
Fig. 82 Wooden corner blocks.