BS5385 2.3 Mosaics.
Mosaics are available in a variety of shapes and sizes, in glazed and unglazed ceramic, glass and marble.
To facilitate ease of handling, mosaics are assembled as sheets, the individual tessera being glued either
face side down to paper (paper-faced mosaics), or bed side down to synthetic mesh, or to small tabs.
Paper-faced mosaics allow full contact to be achieved with the bed, i.e. mortar or adhesive. When sheets
are assembled by means of a backing material it should be made of synthetic fabric, not of cotton or paper.
For a mosaic which has been assembled with backing fabric or tabs it is essential that:
a) the fabric or tabs and their adhesive should not occupy more than 25 % of the area of each tessera.
The
critical factor is the contact of the adhesive over the backs of the tesserae;