Plastic, timber or rubber formliners can be used to provide a variety of surface textures and shapes. Trials to establish the mix and aggregates which provide the required appearance on the broken surface are essential. Full scale trials are essential to achieve a satisfactory result.
An almost unlimited variety of attractive patterns, shapes, and surface textures can be achieved by casting against wood, steel, plaster, elastomeric, plastic, or polystyrene-foam formliners. They can be incorporated into or attached to the surface of a mould.
Ribbed or fluted panels demand considerable attention to detailing as panel sizes and distances between openings must be a multiple of the rib spacing.
Panel joints should normally be in the bottom of a groove or valley. Panels can be produced with vertical ribs or striations in a range of sizes to suit a particular structure and the distance from which it will most often be seen.
For large wall expanses, liner size and characteristics may require that an architectural feature-in the form of a demarcation groove, recess, rib, or plain area-is detailed to hide joints between liners. Otherwise, their use should be limited to less than the available width of the liner, or the liner joints should be designed at form edges.
The cost of liners depends upon the ease of use and the number of reuses obtained. Regardless of the formliner used, draft must be considered to prevent chipping or spalling, during stripping of the unit from the mould.