ADHESIVE - the substance used to stick the tesserae to the backing (substrate).The type of adhesive is reliant upon the type of tesserae or substrate e.g if either is porous. Adhesives may need to be waterproof, water resistant, frostproof or fast setting in some instances. Some adhesives are specifically for indoor or outdoor applications. Common glues are PVA, cement based, silicone and epoxy.
ANDAMENTO - describes the overall flow of the mosaic created by the design lines of the tesserae. The laying down of the tesserae is known as "the opus". Different opus produce a different appearance for the finished object.
BACK BUTTERING - spreading adhesive on the back of the tile before applying it to the substrate. Toothpicks, squeeze bottles and paddle pop sticks can be used as spreaders.
DIRECT METHOD - the design is drawn or transferred onto the substrate and the tesserae are glued directly onto it.
STEP BY STEP: The Direct method for making a trivet - credits: helenmilesmosaics.org
INDIRECT METHOD - tesserae is adhered face down on a temporary surface (e.g paper)with temporary glue. Mortar is then applied to the back of the mosaic design, then flipped onto the final substrate, also prepared with mortar. The Mosaic is then pressed firmly into the mortar to establish a firm bond, and when set, paper is removed.
INTERSTICES - the spaces left between the tesserae also known as a joint. The width affects the design appearance and the amount of grout required
IRIDESCENT - the tiles have a rainbow like surface which appears different colours when seen from different angles. They add a beautiful accent to any project.
JOINT - the space separating the tesserae, generally filled with mortar plaster or grout
KEYING - scoring or roughing up the substrate to better grip the adhesive.
MILLEFIORI - a technique that dates back to Egypt many centuries ago. It is believed that the Egyptians were the first to mix different colours of glass. The process was mastered in Italy and named "million flowers" (mille-fiori). Many slices of glass rods are used and different shapes are made by pressing upon the surface of these rods in order to create a mosaic pattern which is then fused, stretched and sliced into rounds which in cross section reveal the original pattern and may include floral star heart or geometric elements.
OPUS - the laying down of the tesserae is known traditionally as the "opus". Different opus produce a different flow or appearance.
OPUS CIRCUMACTUM - tesserae is applied in fan like patterns usually as a background. This method creates movement.
OPUS CLASSICUM-this technique combines opus tessellatum and opus vermiculatum
OPUS FLUCTUM - a method of laying undulating rows of tesserae. The rows formed weave into each other using triangular tesserae.
OPUS INCERTUM - irregular shaped and randomly placed rocks or uncut stones were placed in a concrete mixture.
OPUS LAPILLI - consisting of small pebbles of many natural colours
Image: Hunting A Lion- 4th Century BC, Pella, Macedonia ( Pella Museum)
OPUS MUSIVUM- the vermiculatum is extended so that the entire area is filled.
OPUS PALLADIUM - the tesserae are laid in an irregular manner sometimes called "crazy paving". It works best if the interstices (gaps) have a regular width.
OPUS REGULATUM - tesserae are laid out in a regular grid, bot horizontally and vertically. This technique is frequently employed when large areas of background need to be filled.
OPUS RETICULATUM - similar to opus tesselatum but with the tesserae arranged in oblique lines
Pompeii
OPUS SCUTULATUM - irregular fragments of stone or polychrome marbles are inserted onto a background of white tesserae.
OPUS SECTILE - one tessera forms a complete shape e.g a star is made from 1 piece of glass
OPUS SIGNINUM - fragments of tiles earthenware pebbles, tiles or tesserae are inserted into a mortar bed. This technique was frequently used in Rome for roads.
OPUS SPICATUM - a Roman technique similar to Regulatum except for the angle of the tesserae which form lines at 45 degrees creating a diagonal rhombus pattern at the base of the mosaic
OPUS TESSELLATUM - tesserae is applied in straight rows, either vertically or horizontally which results in a "brick wall" effect. The tesserae should not line up across both rows. Opus Tessellatum was the most commonly used technique in the production of Hellenistic Roman Early Christian and Byzantine mosaics.
OPUS VERMICULATUM- an outline is created around the motif which creates a halo effect which emphasizes the structure of the design.
PEPPERING - using tesserae of several different hues or colours to scatter at intervals through the main background in order to create interest. It is a good idea to mark on your substrate where the tesserae will go prior to mosaicing.
PIQUE-ASSIETTE / PICASSIETE- (stolen from plate) a style of mosaic that incorporates pieces of broken ceramics such as plates, dishes, cups, vases, tiles, jewellery, figurines, buttons and other found objects.
VIDEO: Broken Plate Mosaics in the Picassiete Tradition
REVERSE METHOD - a temporary surface (brown paper)is used to transfer the mosaic to another substrate. The design is drawn on the brown paper and the tiles are stuck upside down onto the paper using a temporary glue. When completed a layer of adhesive is stuck to the substrate where the mosaic is to be glued. The mosaic on brown paper is pressed down onto the adhesive firmly tile face down. When the adhesive has set the brown paper is dampened with water and peeled off. Any gaps in the grout are filled and then the project is cleaned up as per usual.
VIDEO: Mosaic Classical Technique Reverse Method on Brown Paper Tutorial
SMALTI - traditional hand cut non - moulded mosaic glass . Molten glass is poured into flat slabs which are then broken into rough rectangles with irregular surfaces which may be pitted with air bubbles giving it a different surface appearance from moulded glass. Traditionally smalti is laid very tightly and left ungrouted. Generally between 5mm and 6mm thick, and cut with either a "hammer and hardie (chisel)" or wheeled cutters.
VIDEO: Beginner Smalti Techniques and Tips
SUBSTRATE - The surface onto which the tesserae are glued. The most commonly used is wood. MDF and Plywood of reasonable thickness are suitable as they will not warp. They are best used for indoors and need to be primed and scored before use so the tesserae will adhere.
TESSERAE - are the materials used to create a mosaic design. The materials may consist of glass, ceramic, stone, pebbles, beads, nature based materials, found objects or any combination of these, which can be organised into an arrangement. The tesserae are frequently cut or filed and are then glued to the base (substrate)
TILE ADHESIVE METHOD - the tesserae are pressed into a layer of tile adhesive and there is no need to grout
STEP BY STEP: How to use the Tile Adhesive method. credit: helenmilesmosaics.org.
VITREOUS TILES - square glass mosaic tiles made in molds from glass paste. The top is smooth but the base has ridges to enable better adhesion.
