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Mosaic Glossary of Terms

Adhesive - the medium used to stick the mosaic tile tesserae to the base of the mosaic.  There are a variety of choices depending on the surface used, the tesserae and the mosaics ultimate location.

Andamento - this Italian word means “movement “ or “course”, the term used to describe the flow of lines in a piece of mosaic art achieved by laying the tile in specific lines or ways.

Base – the surface on which the mosaic is installed.  Can be prepared wood,
concrete, concrete board, or any stable, cured and prepared surface.

Back buttering – a technique in which adhesive is applied to the underside of the tesserae as well as or instead of the base.  Back buttering helps to fill to the
level of thinner tesserae so that all the glass is firmly attached to the base.

Cartoon – a pattern or line drawing to use in piecing the mosaic artwork.

Casting frame – a wooden frame that is used to cast concrete slabs using the indirect mosaic method

Curing – the process of drying out cement

Direct method – the technique of creating mosaic where the tesserae are adhered face-up, directly to the base.

Double reverse method – method where the piecing of a mosaic is done face up, then adhered to brown paper or tile tape, flipped over and pre-grouted prior to adhering to the base.

Emblema – decorative mosaic inserts inserted into larger areas such as floors or walls.

EML – expanded metal lathe, inserted in the cement for strength when casting slabs.

Epoxy grout – a two part adhesive grout made of resin and a hardener mixed together just prior to use. This grout is weather resistant. The drawbacks for mosaic artists is that it is expensive, dries darker, has a short pot life and gives off strong fumes until cured.

Frost proof – refers to mosaic materials and techniques that will withstand exposure to weather extremes and conditions.

Smalti Fialti – these are very small pieces of colored glass that are used in micro-mosaics.

Glass gems or nuggets - these are small glass gems sometimes called  “blobs” with flat bases which come in a variety of sizes, styles and colors. 

Grout - the material used to fill in the gaps, or interstices, between the mosaic tesserae. It is an important choice (color of grout is a vital artistic choice with an enormous impact on the final mosaic) in the mosaic process.  It will unify the design as well as protect and stabilize the mosaic.  It is essential to use the correct grout material and process especially if the mosaic is installed outdoors or in wet areas.

Hammer and hardie – traditional mosaic cutting tools usually used for marble and smalti.

Hydrochloric Acid – a strong acid that can be used to clean mosaic tesserae or remove unwanted cement and other materials from the mosaic.

Indirect method – the method where the tesserae are stuck face down on the brown paper or tile tape before being adhered to the base.  This creates a smooth surface.

Interstices – the gaps or spaces between the tesserae.

Key – the cutting process creating a slanted edge to carry the line of tile around a curve.

MDF – this refers to medium density fiberboard a highly compressed wood product that can be used as a base in areas that don’t get wet.

Micromosaics – mosaic using very small tesserae (less than ¼”).

Mortar – this adhesive is made from cement, sand and water used to adhere tesserae to the base.

Opus – this is a Latin word meaning “work” or “creative work.”   It is used to describe the various ways of laying tesserae to create a mosaic work. 

Opus circumactum – refers to a way of laying tesserae using a fan shaped repetitive pattern.

Opus palladianum  -refers to a way of laying tesserae in a random way, also called crazy paving.

Opus regulatum – refers to a way of laying tesserae on a regular or grid pattern.

Opus tesselatum – refers to a way of laying tesserae in brick laying format.

Opus vermiculatum – refers to a way of laying tiles in a winding, flowing sinuous manner.

Pre grouting – the process of grouting from the back (for indirect method of mosaic application) prior to laying the work on the base.

PVA (polyvinyl acetate) - a water based white glue that dries clear.

Scoring – creating a precise score across glass to facilitate cutting or breaking.

Sealing – a solution that is applied to grout and other porous materials to create a water seal.

Smalti – glass tesserae created in many colors.  Smalti are created in a large poured glass “pancake”that are then hand cut into tesserae.

Tesserae – the pieces or materials used in mosaic. 

Thin set – cement based adhesive that is also called mortar.

Vitreous – water proof non porous materials.

Wheeled cutters – tile nippers with wheeled blades.