Rainbow style — Style of mosaic in which the colours of tesserae are arranged in diagonal sequence rather than in rows.
RAMMER — A heavy implement of wood used for pounding down and consolidating wet terrazzo floors.
RAPPEZZO — A portion of a mosaic or terrazzo floor which is made to repair parts which have become worn or have been damaged. Once it is laid, a good rappezzo must not be visible.
Relief — Raised decoration moulded on to the surface of a tile.
RENDER — A mixture of sand and cement applied to a wall or floor as a base for tiles.
REVERSE KEY DRAWING — The reverse key drawing is used in the reverse method on paper; it reproduces mosaic sections in lateral inversion compared with the bozzetto.
ROMAN TECHNIQUE — Mosaic technique developed during the period of the Roman Empire which lasted from 27 BC to 476 AD.
Rosette — Decorative motif in the form of a flower with radiating petals.
RUBBING / CARBORUNDUM STONE — A handheld stone used for smoothing cut edges of a tile or softening edges of cut natural stone tiles.
Rudus — In Roman mosaic, lower layer of mortar in the bedding for a mosaic pavement. It consists of broken bricks mixed with lime which were compacted down, must be at least 20 cm thick.
