Saggar — A fireclay box in which pottery and tiles can be set in a KILN to shield them from direct contact with kiln gases.
Salt glazing — A process whereby the ware is glazed in the kiln. At the height of the firing, salt is thrown into the kiln. This vaporizes and reacts with the clay to form a glaze on the surface of the ware.
SAND — A mix of mineral particles deriving from pre-existing crushed rocks. The sand used for mortars, adhesives or grouts has to be "washed".
SEALER — Protective coating to seal porous tiles such as porcelain, terracotta, natural stone, quarry or slate.
SEALING — Process for preventing porous bases and materials from absorbing moisture and dirt.
sectile — Literally `cut'; commonly used in the phrase 'opus sectile' to signify type of mosaic in which figural patterns are composed of pieces of stone cut in shapes to fit the component parts of the design, thereby differing in approach from the more common type of mosaic in which each shape in the design is composed of tesserae of more or less standard form.
SEMINA — Marble chips (or of other materials) used to make Venetian terrazzo floors.
SETTING BED — Mortar layer on which marble chips are scattered.
Sgraffito — From the Italian for 'scratching'. The technique of scratching through the top layer of a tile with two layers of clay to reveal the colour of the bottom layer.
Signinum — Waterproof mortar containing an aggregate of crushed terracotta, so called after the Italian city of Signia (Segni) in which the technique is said to have been invented.
Silk-screen printing — decoration method commonly used for pottery and tiles. It involves transferring designs onto the surface of the ceramic material using a silk screen.
slaked lime — Chemical compound, also known as hydrated lime, caustic lime, builders' lime, cal, and pickling lime, calcium hydroxide, Ca(OH)2. It is a colorless crystal or white powder and is produced when quicklime (unslaked lime) is mixed with water.
SLATE — Stone composed of shale type rock and clay.
Slip — Thin liquid clay.
SLURRY — A thin, semi-liquid mix of cement, sand and water used as a primer which improves bonding / adhesion.
SMALTO — Smalto (plural - smalti) refers to opaque, coloured glass tesserae.
SNAP CUTTER — Also, score & snap cutter. A manually operated flat board with a scoring wheel used for scoring and snapping tile for cuts.
SPACERS — Plastic pieces in different shapes and sizes that keep tiles equally spaced.
Statumen — In Roman mosaic, the lowest layer of rubble underneath the mortar bedding for a mosaic pavement.
Stencil — A piece of paper, card or metal with a design cut out of it, allowing colour to be applied through the cutaway areas.
Stoneware — Tiles fired at a relatively high temperature resulting in a vitrified body which is both water and frost proof and therefore suitable for use on the exterior of buildings.
SYNTHETIC RESINS — Synthetic resins have been known for a few decades and can solve many different technical problems. There are two groups of synthetic resins: thermoplastic ones (acrylic and vinyl resins) and thermosetting ones (epoxy and phenolic resins).
