ADHESIVE — Generic term for a wide range of substances used to bond tile, tesserae or mosaics to a temporary and / or permanent backing.

Adhesives are regulated by BS EN 12004:2007 and defined by three main criteria: the adhesive chemistry (dispersion, cementitious and reactive resin), the level of performance (normal or improved) and optional characteristics (rapid setting, reduced slip etc).

By far the most common are cementitious adhesives, where the following marks have the following meaning: C = Cementitious (1 = Normal characteristics, 2 = Improved characterises); T = Reduced slip; E = Extended opening time; F = Fast setting; S1 = Deformable, that is deformability between 2.5mm & 5mm; S2 = Highly Deformable, that is deformability of above 5mm.